40 CFR Part 63, Appendix A to Part 63 - Test Methods Pollutant Measurement Methods From Various Waste Media

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Appendix A to Part 63—Test Methods Pollutant Measurement Methods From Various Waste Media
Method 301—Field Validation of
Sec.
Using Method 301
1.0What is the purpose of Method 301?
2.0When must I use Method 301?
3.0What does Method 301 include?
4.0How do I perform Method 301?
Reference Materials
5.0What reference materials must I use?
Sampling Procedures
6.0What sampling procedures must I use?
7.0How do I ensure sample stability?
Bias and Precision
8.0What are the requirements for bias?
9.0What are the requirements for precision?
10.0What calculations must I perform for isotopic spiking?
11.0What calculations must I perform for comparison with a validated method if I am using quadruplet replicate sampling systems?
12.0What calculations must I perform for analyte spiking?
13.0How do I conduct tests at similar sources?
Optional Requirements
14.0How do I use and conduct ruggedness testing?
15.0How do I determine the Limit of Detection (LOD) for the alternative method?
Other Requirements and Information
16.0How do I apply for approval to use an alternative test method?
17.0How do I request a waiver?
18.0Where can I find additional information
Using Method 301
1.0What is the purpose of Method 301?
The purpose of Method 301 is to provide a set of procedures that you, the owner or operator of an affected source subject to requirements under 40 CFR part 63 can use to validate an alternative test method to a test method required in 40 CFR part 63 or to validate a stand-alone alternative test method based on established precision and bias criteria. If you use Method 301 to validate your proposed alternative method, you must use the procedures described in this method. This method describes the minimum procedures that you must use to validate an alternative test method to meet 40 CFR part 63 compliance requirements. If you choose to propose a validation method other than Method 301, you must submit and obtain the Administrator's approval for the alternative validation method.
2.0When must I use Method 301?
If you want to use an alternative test method to meet requirements in a subpart of 40 CFR part 63, you can use Method 301 to validate the alternative test method. You must request approval to use this alternative test method according to the procedures in Sections 16 and 63.7(f). You must receive the Administrator's written approval to use the alternative test method before you use the alternative test method to meet requirements under 40 CFR part 63. In some cases, the Administrator may decide to waive the requirement to use Method 301 for alternative test methods. Section 17 describes the requirements for obtaining a waiver.
3.0What does Method 301 include?
3.1Procedures. This method includes minimum procedures to determine and document systematic error (bias) and random error (precision) of measured concentrations from exhaust gases, wastewater, sludge, and other media. It contains procedures for ensuring sample stability if such procedures are not included in the test method. This method also includes optional procedures for ruggedness and detection limits.
3.2Definitions.
Affected source means affected source as defined in 40 CFR 63.2 and in the relevant subpart under 40 CFR part 63.
Alternative test method means the sampling and analytical methodology selected for field validation using the method described in this appendix.
Paired sampling system means a sampling system capable of obtaining two replicate samples that were collected as closely as possible in sampling time and sampling location.
Quadruplet sampling system means a sampling system capable of obtaining four replicate samples that were collected as closely as possible in sampling time and sampling location.
Surrogate compound means a compound that serves as a model for the types of compounds being analyzed (i.e., similar chemical structure, properties, behavior). The model can be distinguished by the method from the compounds being analyzed.
4.0How do I perform Method 301?
First, you introduce a known concentration of an analyte or compare the alternative test method against a validated test method to determine the alternative test method's bias. Then, you collect multiple, collocated simultaneous samples to determine the alternative test method's precision. Alternatively, though it is not required, we allow validation testing over a broad range of concentrations over an extended time period to determine precision of a proposed alternative method. Sections 5.0 through 17.0 describe the procedures in detail.
Reference Materials
5.0What reference materials must I use?
You must use reference materials (a material or substance whose one or more properties are sufficiently homogenous to the analyte) that are traceable to a national standards body (e.g., National Institute of Standards and Technology (NIST)) at the level of the applicable emission limitation or standard that the subpart in 40 CFR part 63 requires. If you want to expand the applicable range of the method, you must conduct additional runs with higher and lower analyte concentrations. You must obtain information about your analyte according to the procedures in Sections 5.1 through 5.4.
5.1Exhaust Gas Tests Concentration. You must get a known concentration of each analyte from an independent source such as a speciality gas manufacturer, specialty chemical company, or chemical laboratory. You must also get the manufacturer's certification for the analyte concentration and stability.
5.2Tests for Other Waste Media. You must get the pure liquid components of each analyte from an independent manufacturer. The manufacturer must certify the purity and shelf life of the pure liquid components. You must dilute the pure liquid components in the same type medium as the waste from the affected source.
5.3Surrogate Analytes. If you demonstrate to the Administrator's satisfaction that a surrogate compound behaves as the analyte does, then you may use surrogate compounds for highly toxic or reactive compounds. A surrogate may be an isotope or one that contains a unique element (for example, chlorine) that is not present in the source or a derivation of the toxic or reactive compound if the derivative formation is part of the method's procedure. You may use laboratory experiments or literature data to show behavioral acceptability.
5.4Isotopically Labeled Materials. Isotope mixtures may contain the isotope and the natural analyte. The isotope labeled analyte concentration must be more than five times the natural concentration of the analyte.
Sampling Procedures
6.0What sampling procedures must I use?
You may determine bias and precision by comparing against a validated test method, using isotopic sampling, or using analyte spiking (or the equivalent). Isotopic sampling can only be used for procedures requiring mass spectrometry or radiological procedures. You must collect samples according to the requirements in Table 1. You must perform the sampling according to the procedures in Sections 6.1 through 6.4.
6.1Isotopic Spiking. Spike all 12 samples with the analyte at the concentration in the applicable emission limitation or standard in the subpart of 40 CFR part 63. If there is no applicable emission limitation or standard, spike at the expected level of the samples. Follow the appropriate spiking procedures in Sections 6.3.1 through 6.3.2 for the applicable waste medium.
6.2Analyte Spiking. In each quadruplet set, spike half of the samples (two out of the four) with the analyte according to the applicable procedure in Section 6.3.
6.3Spiking Procedure.
6.3.1Gaseous Analyte with Sorbent or Impinger Sampling Trains. Sample the analyte (in the laboratory or in the field) at a concentration that is close to the concentration in the applicable emission limitation or standard in the subpart of 40 CFR Part 63 (or the expected sample concentration where there is no standard) for the time required by the method, and then sample the gas stream for an equal amount of time. The time for sampling both the analyte and gas stream should be equal; however, the time should be adjusted to avoid sorbent breakthrough. The stack gas and the gaseous analyte may be sampled at the same time. The analyte must be introduced as close to the tip of the sampling train as possible.
6.3.2Gaseous Analyte with Sample Container (Bag or Canister). Spike the sample containers after completion of each test run with an amount equal to the concentration in the applicable emission limitation or standard in the subpart of 40 CFR part 63 (or the expected sample concentration where there is no standard). The final concentration of the analyte would be approximately equal to the analyte concentration in the stack plus the applicable emission standard (corrected for spike volume). The volume amount of analyte must be less than 10 percent of the sample volume.
6.3.3Liquid and Solid Analyte with Sorbent or Impinger Trains. Spike the trains with an amount equal to the concentration in the applicable emission limitation or standard in the subpart of 40 CFR part 63 (or the expected sample concentration where there is no standard) before sampling the stack gas. If possible, do the spiking in the field. If it is not possible to do the spiking in the field, you can do it in the laboratory.
6.3.4Liquid and Solid Analyte with Sample Container (Bag or Canister). Spike the containers at the completion of each test run with an amount equal to the concentration in the applicable emission limitation or standard in the subpart of 40 CFR part 63 (or the expected sample concentration where there is no standard).
6.4Probe Placement and Arrangement for Stationary Source Stack or Duct Sampling. To sample a stationary source as defined in 40 CFR 63.2, you must place the probe according to the procedures in this subsection. You must place the probes in the same horizontal plane.
6.4.1Paired Sampling Probes. For paired sampling probes, the probe tip should be 2.5 cm from the outside edge of the other sample probe, with a pitot tube on the outside of each probe. The Administrator may approve a validation request where other paired arrangements for the pitot tube (where required) are used.
6.4.2Quadruplet Sampling Probes. For quadruplet sampling probes, the tips should be in a 6.0 cm × 6.0 cm square area measured from the center line of the opening of the probe tip with a single pitot tube (where required) in the center or two pitot tubes (where required) with their location on either side of the probe tip configuration. You must propose an alternative arrangement whenever the cross-sectional area of the probe tip configuration is approximately five percent or more of the stack or duct cross-sectional area.
7.0How do I ensure sample stability?
7.1Developing Storage and Analysis Procedures. If the alternative test method includes well-established procedures supported by experimental data for sample storage and the time within which the collected samples must be analyzed, you must store the samples according to the procedures in the alternative test method. You are not required to conduct the procedures in Section 7.2 or 7.3. If the alternative test method does not include such procedures, you must propose procedures for storing and analyzing samples to ensure sample stability. At a minimum, your proposed procedures must meet the requirements in Section 7.2 or 7.3. The minimum storage time should be as soon as possible, but no longer than 72 hours after collection of the sample. The maximum storage time should be no longer than two weeks.
7.2Storage and Sampling Procedures for Stack Test Emissions. You must store and analyze samples of stack test emissions according to Table 3. If you are using analyte spiking procedures, you must include equal numbers of spiked and unspiked samples.
7.3Storage and Sampling Procedures for Testing Other Waste Media (e.g., Soil/Sediment, Solid Waste, Water/Liquid). You must analyze half of the replicate samples at the proposed minimum storage time and the other half at the proposed maximum storage time or within two weeks of the initial analysis to identify the effect of storage times on analyte samples. The minimum storage time should be as soon as possible, but no longer than seven days after collection of the sample.
7.4Sample Stability. After you have conducted sampling and analysis according to Section 7.2 or 7.3, compare the results at the minimum and maximum storage times. Calculate the difference in the results using Equation 301-1.
Where:
di = difference between the results of the ith sample.
Rmini = results from the ith sample at the minimum storage time.
Rmaxi = results from the ith sample at the maximum storage time.
7.4.1Standard Deviation. Determine the standard deviation (SDd) of the differences (di's) of the paired samples using Equation 301-2.
Where:
di = The difference between the results of the ith sample, Rmini − Rmaxi.
dm = The mean of the paired sample differences.
n = Total number of paired samples.
7.4.2t Test. Test the difference in the results for statistical significance by calculating the t-statistic and determining if the mean of the differences between the initial results and the results after storage is significant at the 95 percent confidence level and n − 1 degrees of freedom. Calculate the value of the t-statistic using Equation 301-3.
Where:
n = The total number of paired samples.
Compare the calculated t-statistic with the critical value of the t-statistic from Table 2. If the calculated t-value is less than the critical value, the difference is not statistically significant; thus, the sampling and analysis procedure ensures stability, and you may submit a request for validation of the proposed alternative test method. If the calculated t-value is greater than the critical value, the difference is statistically significant, and you must repeat the procedures in Section 7.2 or 7.3 with new samples using shorter proposed maximum storage times.
Bias and Precision
8.0What are the requirements for bias?
You must establish bias by comparing the results of the sampling using the alternative test method against a reference value. The bias must be no more than ±10 percent without the use of correction factors, and no more than ±30 percent with the use of correction factors for bias values between 10 and 30 percent for the alternative test method to be acceptable.
9.0What are the requirements for precision?
At a minimum, you must use paired sampling systems to establish precision. If you are using analyte spiking, including isotopic samples, the precision expressed as the relative standard deviation (RSD) of the alternative test method at the level of the applicable emission limitation or standard in the subpart of 40 CFR part 63 must be less than or equal to 20 percent. For samples with a precision greater than 20 percent but less than 50 percent, a minimum of nine sample runs will be required. If you are comparing to a validated test method, the alternative test method must be at least as precise as the validated method at the level of the applicable emission limitation or standard in the subpart of 40 CFR part 63 as determined by an F test (Section 11.2.2).
10.0What calculations must I perform for isotopic spiking?
You must analyze the bias, precision, relative standard deviation, and data acceptance for isotopic spiking tests according to the provisions in Sections 10.1 through 10.3.
10.1Numerical Bias. Calculate the numerical value of the bias using the results from the analysis of the isotopically spiked field samples and the calculated value of the isotopically labeled spike according to Equation 301-4.
Where:
B = Bias at the spike level.
Sm = Mean of the measured values of the isotopically spiked samples.
CS = Calculated value of the isotopically labeled spike.
10.2Standard Deviation. Calculate the standard deviation of the Si values according to Equation 301-5.
Where:
Si = Measured value of the isotopically labeled analyte in the i-th field sample,
n = Number of isotopically spiked samples, 12.
10.3t Test. Test the bias for statistical significance by calculating the t-statistic using Equation 301-6. Use the standard deviation determined in Section 10.2 and the numerical bias determined in Section 10.1.
Compare the calculated t-value with the critical value of the two-sided t-distribution at the 95 percent confidence level and n-1 degrees of freedom. When spiking is conducted according to the procedures specified in Sections 6.2 and 6.4 as required, this critical value is 2.201 for the 11 degrees of freedom. If the calculated t-value is less than the critical value, the bias is not statistically significant, and the bias of the candidate test method is acceptable. If the calculated t-value is greater than the critical value, the bias is statistically significant, and you must evaluate the relative magnitude of the bias using Equation 301-7.
Where:
BR = Relative bias.
If the relative bias is less than or equal to ten percent, the bias of the candidate test method is acceptable and no correction factors are required. If the relative bias is greater than 10 percent but less than 30 percent, and if you correct all future data collected with the method for the magnitude of the bias, the bias of the candidate test method is acceptable. If either of the preceding two cases applies, you may continue to evaluate the method by calculating its precision. If not, the candidate method will not meet the requirements of Method 301.
10.4Relative Standard Deviation. Calculate the RSD according to Equation 301-8.
Where:
Sm = The measured mean of the isotopically labeled spiked samples.
The data and alternative test method are unacceptable if the RSD is greater than 20 percent.
11.0What calculations must I perform for comparison with a validated method if I am using quadruplet replicate sampling systems?
If you are using quadruplet replicate sampling systems to compare an alternative test method to a validated method, then you must analyze the data according to the provisions in this section. If the data from the alternative test method fail either the bias or precision test, the data and the alternative test method are unacceptable. If the Administrator determines that the affected source has highly variable emission rates, the Administrator may require additional precision checks.
11.1Bias Analysis. Test the bias for statistical significance at the 95 percent confidence level by calculating the t-statistic.
11.1.1Bias. Determine the bias, which is defined as the mean of the differences between the alternative test method and the validated method (dm). Calculate di according to Equation 301-9.
Where:
V1i = First measured value with the validated method in the i-th sample.
V2i = Second measured value with the validated method in the i-th sample.
P1i = First measured value with the alternative test method in the i-th sample.
2i = Second measured value with the alternative test method in the i-th sample.
11.1.2Standard Deviation of the Differences. Calculate the standard deviation of the differences, SDd, using Equation 301-2.
11.1.3t Test. Calculate the t-statistic using Equation 301-3, where n is the total number of test sample differences (di). For the quadruplet sampling system procedure in Section 6.1 and Table 1, n equals four. Compare the calculated t-statistic with the critical value of the t-statistic, and determine if the bias is significant at the 95 percent confidence level. When four runs are conducted, as specified in Section 6.2 and Table 1, the critical value of the t-statistic is 3.182 for three degrees of freedom. If the calculated t-value is less than the critical value, the bias is not statistically significant and the data are acceptable. If the calculated t-value is greater than the critical value, the bias is statistically significant, and you must evaluate the relative magnitude of the bias using Equation 301-10.
Where:
B = Bias − mean of the di's.
VS = Mean measured by the validated method.
If the relative bias is less than or equal to 10 percent, the bias of the candidate test method is acceptable and no correction factors are required. If the relative bias is greater than 10 percent but less than 30 percent, and if you correct all future data collected with the method for the magnitude of the bias, the bias of the candidate test method is acceptable. If either of the preceding two cases applies, you may continue to evaluate the method by calculating its precision. If not, the candidate method will not meet the requirements of Method 301.
11.2Precision. Compare the estimated variance (or standard deviation) of the alternative test method to that of the validated method. If a significant difference is determined using the F test, the alternative test method and the results are rejected. If the F test does not show a significant difference, then the alternative test method has acceptable precision. Use the value furnished with the method. Calculate the estimated variance of the validated method using Equation 301-11.
11.2.1Alternative Test Method Variance. Calculate the estimated variance of the alternative test method, Sp 2, according to Equation 301-11.
Where:
di = The difference between the i-th pair of samples collected with the alternative test method.
n = Number of samples and the degrees of freedom.
11.2.2F Test. Determine if the estimated variance of the alternative test method is greater than that of the validated method by calculating the F-value using Equation 301-12.
Where:
Sp 2 = The estimated variance of the alternative method.
Sv 2 = The estimated variance of the validated method.
Compare the experimental F value with the one-sided confidence level for F. The one-sided confidence level of 95 percent for F is 6.388 when the procedure specified in Section 6.1 and Table 1 for quadruplet trains is followed. If the calculated F is outside the critical range, the difference in precision is significant, and the data and the candidate test method are unacceptable.
12.0What calculations must I perform for analyte spiking?
You must analyze the data for analyte spike testing according to this section.
12.1Bias Analysis. Test the bias for statistical significance at the 95 percent confidence level by calculating the t-statistic.
12.1.1Bias. Determine the bias using the results from the analysis of the spiked field samples, the unspiked field samples, and the calculated value of the spike using Equation 301-13.
Where:
S1i = First measured value of the ith spiked sample.
S2i = Second measured value of the ith spiked sample.
M1i = First measured value of the ith unspiked sample.
M2i = Second measured value of the ith unspiked sample.
CS = Calculted value of the spiked level.
12.1.2Standard Deviation of the Differences. Calculate the standard deviation of the differences, SDd, using Equation 301-2.
12.1.3t Test. Calculate the t-statistic using Equation 301-3, where n is the total number of test sample differences (di). For the quadruplet sampling system procedure in Table 1, n equals six. Compare the calculated t-statistic with the critical value of the t-statistic, and determine if the bias is significant at the 95 percent confidence level. When six runs are conducted, as specified in Table 1, the two-sided confidence level critical value is 2.571 for the five degrees of freedom. If the relative bias is less than or equal to 10 percent with no correction factors, or the bias is greater than 10 percent but less than 30 percent with the use of correction factors, then the data are acceptable. Proceed to evaluate precision of the candidate test method.
Where:
B = Bias − mean of the di's.
VS = Mean measured by the validated method.
12.2Precision. Calculate the standard deviation and the relative standard deviation of the candidate test method. The relative standard deviation of the candidate test method can be calculated using Equation 301-8.
13.0How do I conduct tests at similar sources?
If the Administrator has approved the use of an alternative test method to a test method required in 40 CFR part 63 for an affected source, and the Administrator has approved the use of the alternative test method at your similar source according to the procedures in Section 17.1.1, you must meet the requirements in this section. You must have at least three replicate samples for each test that you conduct at the similar source. You must average the results of the samples to determine the pollutant concentration.
Optional Requirements
14.0How do I use and conduct ruggedness testing?
If you want to use a validated test method at a concentration that is different from the concentration in the applicable emission limitation in the subpart of 40 CFR part 63 or for a source category that is different from the source category that the test method specifies, then you must conduct ruggedness testing according to the procedures in Citation 18.16 of Section 18.0 and submit a request for a waiver according to Section 17.1.1.
Ruggedness testing is a laboratory study to determine the sensitivity of a method to parameters such as sample collection rate, interferant concentration, collecting medium temperature, and sample recovery temperature. You conduct ruggedness testing by changing several variables simultaneously instead of changing one variable at a time. For example, you can determine the effect of seven variables in eight experiments instead of one. (W.J. Youden, Statistical Manual of the Association of Official Analytical Chemists, Association of Official Analytical Chemists, Washington, DC, 1975, pp. 33-36).
15.0How do I determine the Limit of Detection for the alternative method?
15.1Limit of Detection. The Limit of Detection (LOD) is the lowest level above which you may obtain quantitative results with an acceptable degree of confidence. For this protocol, the LOD is defined as three times the standard deviation, So, at the blank level.
15.2Purpose. The LOD will be used to establish the lower limit of the test method. If the estimated LOD is no more than twice the calculated LOD, use Procedure I in Table 4 to determine So. If the LOD is greater than twice the calculated LOD, use Procedure II in Table 4 to determine So. For radiochemical methods, use the Multi-Agency Radiological Laboratory Analytical Protocols (MARLAP) Manual (i.e., use the minimum detectable concentration (MDC) and not the LOD) available at http://www.epa.gov/radiation/docs/marlap/402-b-04-001c-20_final.pdf.
Other Requirements and Information
16.0How do I apply for approval to use an alternative test method?
16.1 Submitting Requests. You must request to use an alternative test method according to the procedures in Section 63.7(f). You may not use an alternative test method to meet any requirement under 40 CFR part 63 until the Administrator has approved your request. The request must include a field validation report containing the information in Section 16.2. The request must be submitted to the Director, Air Quality Assessment Division, U.S. Environmental Protection Agency, C304-02, Research Triangle Park, NC 27711.
16.2Field Validation Report. The field validation report must contain the information in Sections 16.2.1 through 16.2.8.
16.2.1Regulatory objectives for the testing, including a description of the reasons for the test, applicable emission limits, and a description of the source.
16.2.2Summary of the results and calculations shown in Sections 6.0 through 16, as applicable.
16.2.3Analyte certification and value(s).
16.2.4Discussion of laboratory evaluations.
16.2.5Discussion of field sampling.
16.2.6Discussion of sample preparations and analysis.
16.2.7Storage times of samples (and extracts, if applicable).
16.2.8Reasons for eliminating any results.
17.0How do I request a waiver?
17.1Conditions for Waivers. If you meet one of the criteria in Sections 17.1.1 through 17.1.2, the Administrator may waive the requirement to use the procedures in this method to validate an alternative test method. In addition, if EPA currently recognizes an appropriate test method or considers the analyst's test method to be satisfactory for a particular source, the Administrator may waive the use of this protocol or may specify a less rigorous validation procedure.
17.1.1Similar Sources. If the alternative test method that you want to use has been validated at another source and you can demonstrate to the Administrator's satisfaction that your affected source is similar to that source, then the Administrator may waive the requirement for you to validate the alternative test method. One procedure you may use to demonstrate the applicability of the method to your affected source is by conducting a ruggedness test as described in Section 14.0.
17.1.2Documented Methods. If the bias and precision of the alternative test method that you are proposing have been demonstrated through laboratory tests or protocols different from this method, and you can demonstrate to the Administrator's satisfaction that the bias and precision apply to your application, then the Administrator may waive the requirement to use this method or to use part of this method.
17.2Submitting Applications for Waivers. You must sign and submit each request for a waiver from the requirements in this method in writing. The request must be submitted to the Director, Air Quality Assessment Division, U.S. Environmental Protection Agency, C304-02, Research Triangle Park, NC 27711.
17.3Information Application for Waiver. The request for a waiver must contain a thorough description of the test method, the intended application, and results of any validation or other supporting documents. The request for a waiver must contain, at a minimum, the information in Sections 17.3.1 through 17.3.4. The Administrator may request additional information if necessary to determine whether this method can be waived for a particular application.
17.3.1A Clearly Written Test Method. The method should be written preferably in the format of 40 CFR part 60, Appendix A Test Methods. It must include an applicability statement, concentration range, precision, bias (accuracy), and minimum and maximum storage time in which samples must be analyzed.
17.3.2Summaries of previous validation tests or other supporting documents. If a different procedure from that described in this method was used, you must submit documents substantiating the bias and precision values to the Administrator's satisfaction.
17.3.3Ruggedness Testing Results. You must submit results of ruggedness testing conducted according to Section 14.0, sample stability conducted according to Section 7.0, and detection limits conducted according to Section 15.0, as applicable. For example, you would not need to submit ruggedness testing results if you will be using the method at the same concentration level as the concentration level at which it was validated.
17.3.4Applicability Statement and Basis for Waiver Approval. Your discussion of the applicability statement and basis for approval of the waiver should address the following as applicable: Applicable regulation, emission standards, effluent characteristics, and process operations.
18.0Where can I find additional information?
You can find additional information in the references in Sections 18.1 through 18.16.
18.1Albritton, J.R., G.B. Howe, S.B. Tompkins, R.K.M. Jayanty, and C.E. Decker. 1989. Stability of Parts-Per-Million Organic Cylinder Gases and Results of Source Test Analysis Audits, Status Report No. 11. Environmental Protection Agency Contract 68-02-4125. Research Triangle Institute, Research Triangle Park, NC. September.
18.2ASTM Standard E 1169-89 (current version), “Standard Guide for Conducting Ruggedness Tests,” available from ASTM, 100 Barr Harbor Drive, West Conshohoken, PA 19428.
18.3DeWees, W.G., P.M. Grohse, K.K. Luk, and F.E. Butler. 1989. Laboratory and Field Evaluation of a Methodology for Speciating Nickel Emissions from Stationary Sources. EPA Contract 68-02-4442. Prepared for Atmospheric Research and Environmental Assessment Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. January.
18.4International Conference on Harmonization of Technical Requirements for the Registration of Pharmaceuticals for Human Use, ICH-Q2A, “Text on Validation of Analytical Procedures,” 60 FR 11260 (March 1995).
18.5International Conference on Harmonization of Technical Requirements for the Registration of Pharmaceuticals for Human Use, ICH-Q2b, “Validation of Analytical Procedures: Methodology,” 62 FR 27464 (May 1997).
18.6Keith, L.H., W. Crummer, J. Deegan Jr., R.A. Libby, J.K. Taylor, and G. Wentler. 1983. Principles of Environmental Analysis. American Chemical Society, Washington, DC.
18.7Maxwell, E.A. 1974. Estimating variances from one or two measurements on each sample. Amer. Statistician 28:96-97.
18.8Midgett, M.R. 1977. How EPA Validates NSPS Methodology. Environ. Sci. & Technol. 11(7):655-659.
18.9Mitchell, W.J., and M.R. Midgett. 1976. Means to evaluate performance of stationary source test methods. Environ. Sci. & Technol. 10:85-88.
18.10Plackett, R.L., and J.P. Burman. 1946. The design of optimum multifactorial experiments. Biometrika, 33:305.
18.11Taylor, J.K. 1987. Quality Assurance of Chemical Measurements. Lewis Publishers, Inc., pp. 79-81.
18.12U.S. Environmental Protection Agency. 1978. Quality Assurance Handbook for Air Pollution Measurement Systems: Volume III. Stationary Source Specific Methods. Publication No. EPA-600/4-77-027b. Office of Research and Development Publications, 26 West St. Clair St., Cincinnati, OH 45268.
18.13U.S. Environmental Protection Agency. 1981. A Procedure for Establishing Traceability of Gas Mixtures to Certain National Bureau of Standards Standard Reference Materials. Publication No. EPA-600/7-81-010. Available from the U.S. EPA, Quality Assurance Division (MD-77), Research Triangle Park, NC 27711.
18.14U.S. Environmental Protection Agency. 1991. Protocol for The Field Validation of Emission Concentrations From Stationary Sources. Publication No. 450/4-90-015. Available from the U.S. EPA, Emission Measurement Technical Information Center, Technical Support Division (MD-14), Research Triangle Park, NC 27711.
18.15Wernimont, G.T., “Use of Statistics to Develop and Evaluate Analytical Methods,” AOAC, 1111 North 19th Street, Suite 210, Arlington, VA 22209. USA, 78-82 (1987).
18.16Youden, W.J. Statistical techniques for collaborative tests. Statistical Manual of the Association of Official Analytical Chemists, Association of Official Analytical Chemists, Washington, DC, 1975, pp. 33-36.
Table 1 to Appendix A—Sampling Procedures
If you are . . . You must collect . . .
comparing against a validated method 9 sets of replicate samples using a paired sampling system (a total of 18 samples) or 4 sets of replicate samples using a quadruplet sampling system (a total of 16 samples). In each sample set, you must use the validated test method to collect and analyze half of the samples.
using isotopic spiking (can only be used for procedures requiring mass spectrometry) a total of 12 replicate samples. You may collect the samples either by obtaining 6 sets of paired samples or 3 sets of quadruplet samples.
using analyte spiking a total of 24 samples using the quadruplet sampling system (a total of 6 sets of replicate samples).
Table 2 to Appendix A—Critical Values of t for the Two Tailed 95 Percent Confidence Limit
Degrees of freedom t95
1 12.706
2 4.303
3 3.182
4 2.776
5 2.571
6 2.447
7 2.365
8 2.306
9 2.262
10 2.228
Table 3 to Appendix A—Storage and Sampling Procedures for Stack Test Emissions
If you are . . . With . . . Then you must . . .
using isotopic or analyte spiking procedures sample container (bag or canister) and impinger sampling systems analyze 6 of the samples within 7 days and then analyze the same 6 samples at the proposed maximum storage time or 2 weeks after the initial analysis.
sorbent and impinger sampling systems that require extraction or digestion extract or digest 6 of the samples within 7 days and extract or digest 6 other samples at the proposed maximum storage time or 2 weeks after the first extraction or digestion. Analyze an aliquot of the first 6 extracts (digestates) within 7 days and proposed maximum storage times or 2 weeks after the initial analysis. This will allow analysis of extract storage impacts.
sorbent sampling systems that require thermal desorption analyze 6 samples within 7 days. Analyze another set of 6 samples at the proposed maximum storage time or within 2 weeks of the initial analysis.
comparing an alternative test method against a validated test method sampling method that does not include sorbent and impinger sampling systems that require extraction or digestion analyze half of the samples (8 or 9) within 7 days and half of the samples (8 or 9) at the proposed maximum storage time or within 2 weeks of the initial analysis.
sorbent and impinger sampling systems that require extraction or digestion extract or digest 6 of the samples within 7 days and extract or digest 6 other samples at the proposed maximum storage time or within 2 weeks of the first extraction or digestion. Analyze an aliquot of the first 6 extracts (digestates) within 7 days and at the proposed maximum storage times or within 2 weeks of the initial analysis. This will allow analysis of extract storage impacts.
Table 4 to Appendix A—Procedures for Estimating So
If the estimated LOD (LOD1, expected approximate LOD concentration level) is no more than twice the calculated LOD, use Procedure I as follows. Estimate the LOD (LOD1) and prepare a test standard at this level. The test standard could consist of a dilution of the analyte described in Section 5.0 If the estimated LOD (LOD1, expected approximate LOD concentration level) is greater than twice the calculated LOD, use Procedure II as follows. Prepare two additional standards (LOD2 and LOD3) at concentration levels lower than the standard used in Procedure I (LOD1).
Using the normal sampling and analytical procedures for the method, sample and analyze this standard at least 7 times in the laboratory Sample and analyze each of these standards (LOD2 and LOD3) at least 7 times.
Calculate the standard deviation, S1, of the measured values Calculate the standard deviation (S2 and S3) for each concentration level.
Calculate the LOD0 (referred to as the calculated LOD) as 3 times S1, where S0 = S1 Plot the standard deviations of the three test standards (S1, S2 and S3) as a function of concentration.
Draw a best-fit straight line through the data points and extrapolate to zero concentration. The standard deviation at zero concentration is So.
Calculate the LOD0 (referred to as the calculated LOD) as 3 times So.
Method 303—Determination of Visible Emissions From By-Product Coke Oven Batteries
Note:
This method is not inclusive with respect to observer certification. Some material is incorporated by reference from other methods in appendix A to 40 CFR part 60. Therefore, to obtain reliable results, persons using this method should have a thorough knowledge of Method 9.
1.0Scope and Application
1.1Applicability. This method is applicable for the determination of visible emissions (VE) from the following by-product coke oven battery sources: charging systems during charging; doors, topside port lids, and offtake systems on operating coke ovens; and collecting mains. This method is also applicable for qualifying observers for visually determining the presence of VE. In order for the test method results to be indicative of plant performance, the time of day of the run should vary.
2.0Summary of Method
2.1A certified observer visually determines the VE from coke oven battery sources. Certification procedures are presented. This method does not require that opacity of emissions be determined or that magnitude be differentiated.
3.0Definitions
3.1Bench means the platform structure in front of the oven doors.
3.2By-product Coke Oven Battery means a source consisting of a group of ovens connected by common walls, where coal undergoes destructive distillation under positive pressure to produce coke and coke oven gas, from which by-products are recovered.
3.3Charge or charging period means the period of time that commences when coal begins to flow into an oven through a topside port and ends when the last charging port is recapped.
3.4Charging system means an apparatus used to charge coal to a coke oven (e.g., a larry car for wet coal charging systems).
3.5Coke oven door means each end enclosure on the push side and the coking side of an oven. The chuck, or leveler-bar, door is considered part of the push side door. The coke oven door area includes the entire area on the vertical face of a coke oven between the bench and the top of the battery between two adjacent buck stays.
3.6Coke side means the side of a battery from which the coke is discharged from ovens at the end of the coking cycle.
3.7Collecting main means any apparatus that is connected to one or more offtake systems and that provides a passage for conveying gases under positive pressure from the by-product coke oven battery to the by-product recovery system.
3.8Consecutive charges means charges observed successively, excluding any charge during which the observer's view of the charging system or topside ports is obscured.
3.9Damper-off means to close off the gas passage between the coke oven and the collecting main, with no flow of raw coke oven gas from the collecting main into the oven or into the oven's offtake system(s).
3.10Decarbonization period means the period of time for combusting oven carbon that commences when the oven lids are removed from an empty oven or when standpipe caps of an oven are opened. The period ends with the initiation of the next charging period for that oven.
3.11Larry car means an apparatus used to charge coal to a coke oven with a wet coal charging system.
3.12Log average means logarithmic average as calculated in Section 12.4.
3.13Offtake system means any individual oven apparatus that is stationary and provides a passage for gases from an oven to a coke oven battery collecting main or to another oven. Offtake system components include the standpipe and standpipe caps, goosenecks, stationary jumper pipes, mini-standpipes, and standpipe and gooseneck connections.
3.14Operating oven means any oven not out of operation for rebuild or maintenance work extensive enough to require the oven to be skipped in the charging sequence.
3.15Oven means a chamber in the coke oven battery in which coal undergoes destructive distillation to produce coke.
3.16Push side means the side of the battery from which the coke is pushed from ovens at the end of the coking cycle.
3.17Run means the observation of visible emissions from topside port lids, offtake systems, coke oven doors, or the charging of a single oven in accordance with this method.
3.18Shed means an enclosure that covers the side of the coke oven battery, captures emissions from pushing operations and from leaking coke oven doors on the coke side or push side of the coke oven battery, and routes the emissions to a control device or system.
3.19Standpipe cap means An apparatus used to cover the opening in the gooseneck of an offtake system.
3.20Topside port lid means a cover, removed during charging or decarbonizing, that is placed over the opening through which coal can be charged into the oven of a by-product coke oven battery.
3.21Traverse time means accumulated time for a traverse as measured by a stopwatch. Traverse time includes time to stop and write down oven numbers but excludes time waiting for obstructions of view to clear or for time to walk around obstacles.
3.22Visible Emissions or VE means any emission seen by the unaided (except for corrective lenses) eye, excluding steam or condensing water.
4.0Interferences [Reserved]
5.0Safety
5.1Disclaimer. This method may involve hazardous materials, operations, and equipment. This test method may not address all of the safety problems associated with its use. It is the responsibility of the user of this test method to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to performing this test method.
5.2Safety Training. Because coke oven batteries have hazardous environments, the training materials and the field training (Section 10.0) shall cover the precautions required by the company to address health and safety hazards. Special emphasis shall be given to the Occupational Safety and Health Administration (OSHA) regulations pertaining to exposure of coke oven workers (see Reference 3 in Section 16.0). In general, the regulation requires that special fire-retardant clothing and respirators be worn in certain restricted areas of the coke oven battery. The OSHA regulation also prohibits certain activities, such as chewing gum, smoking, and eating in these areas.
6.0Equipment and Supplies [Reserved]
7.0Reagents and Standards [Reserved]
8.0Sample Collection, Preservation, Transport, and Storage [Reserved]
9.0Quality Control [Reserved]
10.0Calibration and Standardization
Observer certification and training requirements are as follows:
10.1Certification Procedures. This method requires only the determination of whether VE occur and does not require the determination of opacity levels; therefore, observer certification according to Method 9 in appendix A to part 60 of this chapter is not required to obtain certification under this method. However, in order to receive Method 303 observer certification, the first-time observer (trainee) shall have attended the lecture portion of the Method 9 certification course. In addition, the trainee shall successfully complete the Method 303 training course, satisfy the field observation requirement, and demonstrate adequate performance and sufficient knowledge of Method 303. The Method 303 training course shall be conducted by or under the sanction of the EPA and shall consist of classroom instruction and field observations, and a proficiency test.
10.1.1The classroom instruction shall familiarize the trainees with Method 303 through lecture, written training materials, and a Method 303 demonstration video. A successful completion of the classroom portion of the Method 303 training course shall be demonstrated by a perfect score on a written test. If the trainee fails to answer all of the questions correctly, the trainee may review the appropriate portion of the training materials and retake the test.
10.1.2The field observations shall be a minimum of 12 hours and shall be completed before attending the Method 303 certification course. Trainees shall observe the operation of a coke oven battery as it pertains to Method 303, including topside operations, and shall also practice conducting Method 303 or similar methods. During the field observations, trainees unfamiliar with coke battery operations shall receive instruction from an experienced coke oven observer familiar with Method 303 or similar methods and with the operation of coke batteries. The trainee must verify completion of at least 12 hours of field observation prior to attending the Method 303 certification course.
10.1.3All trainees must demonstrate proficiency in the application of Method 303 to a panel of three certified Method 303 observers, including an ability to differentiate coke oven emissions from condensing water vapor and smoldering coal. Each panel member shall have at least 120 days experience in reading visible emissions from coke ovens. The visible emissions inspections that will satisfy the experience requirement must be inspections of coke oven battery fugitive emissions from the emission points subject to emission standards under subpart L of this part (i.e., coke oven doors, topside port lids, offtake system(s), and charging operations), using either Method 303 or predecessor State or local test methods. A “day's experience” for a particular inspection is a day on which one complete inspection was performed for that emission point under Method 303 or a predecessor State or local method. A “day's experience” does not mean 8 or 10 hours performing inspections, or any particular time expressed in minutes or hours that may have been spent performing them. Thus, it would be possible for an individual to qualify as a Method 303 panel member for some emission points, but not others (e.g., an individual might satisfy the experience requirement for coke oven doors, but not topside port lids). Until November 15, 1994, the EPA may waive the certification requirement (but not the experience requirement) for panel members. The composition of the panel shall be approved by the EPA. The panel shall observe the trainee in a series of training runs and a series of certification runs. There shall be a minimum of 1 training run for doors, topside port lids, and offtake systems, and a minimum of 5 training runs (i.e., 5 charges) for charging. During training runs, the panel can advise the trainee on proper procedures. There shall be a minimum of 3 certification runs for doors, topside port lids, and offtake systems, and a minimum of 15 certification runs for charging (i.e., 15 charges). The certifications runs shall be unassisted. Following the certification test runs, the panel shall approve or disapprove certification based on the trainee's performance during the certification runs. To obtain certification, the trainee shall demonstrate to the satisfaction of the panel a high degree of proficiency in performing Method 303. To aid in evaluating the trainee's performance, a checklist, provided by the EPA, will be used by the panel members.
10.2Observer Certification/Recertification. The coke oven observer certification is valid for 1 year from date of issue. The observer shall recertify annually by viewing the training video and answering all of the questions on the certification test correctly. Every 3 years, an observer shall be required to pass the proficiency test in Section 10.1.3 in order to be certified.
10.3The EPA (or applicable enforcement agency) shall maintain records reflecting a certified observer's successful completion of the proficiency test, which shall include the completed proficiency test checklists for the certification runs.
10.4An owner or operator of a coke oven battery subject to subpart L of this part may observe a training and certification program under this section.
11.0Procedure
11.1Procedure for Determining VE from Charging Systems During Charging.
11.1.1Number of Oven Charges. Refer to § 63.309(c)(1) of this part for the number of oven charges to observe. The observer shall observe consecutive charges. Charges that are nonconsecutive can only be observed when necessary to replace observations terminated prior to the completion of a charge because of visual interferences. (See Section 11.1.5).
11.1.2Data Records. Record all the information requested at the top of the charging system inspection sheet (Figure 303-1). For each charge, record the identification number of the oven being charged, the approximate beginning time of the charge, and the identification of the larry car used for the charge.
11.1.3Observer Position. Stand in an area or move to positions on the topside of the coke oven battery with an unobstructed view of the entire charging system. For wet coal charging systems or non-pipeline coal charging systems, the observer should have an unobstructed view of the emission points of the charging system, including larry car hoppers, drop sleeves, and the topside ports of the oven being charged. Some charging systems are configured so that all emission points can only be seen from a distance of five ovens. For other batteries, distances of 8 to 12 ovens are adequate.
11.1.4Observation. The charging period begins when coal begins to flow into the oven and ends when the last charging port is recapped. During the charging period, observe all of the potential sources of VE from the entire charging system. For wet coal charging systems or non-pipeline coal charging systems, sources of VE typically include the larry car hoppers, drop sleeves, slide gates, and topside ports on the oven being charged. Any VE from an open standpipe cap on the oven being charged is included as charging VE.
11.1.4.1Using an accumulative-type stopwatch with unit divisions of at least 0.5 seconds, determine the total time VE are observed as follows. Upon observing any VE emerging from any part of the charging system, start the stopwatch. Stop the watch when VE are no longer observed emerging, and restart the watch when VE reemerges.
11.1.4.2When VE occur simultaneously from several points during a charge, consider the sources as one. Time overlapping VE as continuous VE. Time single puffs of VE only for the time it takes for the puff to emerge from the charging system. Continue to time VE in this manner for the entire charging period. Record the accumulated time to the nearest 0.5 second under “Visible emissions, seconds” on Figure 303-1.
11.1.5Visual Interference. If fugitive VE from other sources at the coke oven battery site (e.g., door leaks or condensing water vapor from the coke oven wharf) prevent a clear view of the charging system during a charge, stop the stopwatch and make an appropriate notation under “Comments” on Figure 303-1. Label the observation an observation of an incomplete charge, and observe another charge to fulfill the requirements of Section 11.1.1.
11.1.6VE Exemptions. Do not time the following VE:
11.1.6.1The VE from burning or smoldering coal spilled on top of the oven, topside port lid, or larry car surfaces;
Note:
The VE from smoldering coal are generally white or gray. These VE generally have a plume of less than 1 meter long. If the observer cannot safely and with reasonable confidence determine that VE are from charging, do not count them as charging emissions.
11.1.6.2The VE from the coke oven doors or from the leveler bar; or
11.1.6.3The VE that drift from the top of a larry car hopper if the emissions had already been timed as VE from the drop sleeve.
Note:
When the slide gate on a larry car hopper closes after the coal has been added to the oven, the seal may not be airtight. On occasions, a puff of smoke observed at the drop sleeves is forced past the slide gate up into the larry car hopper and may drift from the top; time these VE either at the drop sleeves or the hopper. If the larry car hopper does not have a slide gate or the slide gate is left open or partially closed, VE may quickly pass through the larry car hopper without being observed at the drop sleeves and will appear as a strong surge of smoke; time these as charging VE.
11.1.7Total Time Record. Record the total time that VE were observed for each charging operation in the appropriate column on the charging system inspection sheet.
11.1.8Determination of Validity of a Set of Observations. Five charging observations (runs) obtained in accordance with this method shall be considered a valid set of observations for that day. No observation of an incomplete charge shall be included in a daily set of observations that is lower than the lowest reading for a complete charge. If both complete and incomplete charges have been observed, the daily set of observations shall include the five highest values observed. Four or three charging observations (runs) obtained in accordance with this method shall be considered a valid set of charging observations only where it is not possible to obtain five charging observations, because visual interferences (see Section 11.1.5) or inclement weather prevent a clear view of the charging system during charging. However, observations from three or four charges that satisfy these requirements shall not be considered a valid set of charging observations if use of such set of observations in a calculation under Section 12.4 would cause the value of A to be less than 145.
11.1.9Log Average. For each day on which a valid daily set of observations is obtained, calculate the daily 30-day rolling log average of seconds of visible emissions from the charging operation for each battery using these data and the 29 previous valid daily sets of observations, in accordance with Section 12.4.
11.2.Procedure for Determining VE from Coke Oven Door Areas. The intent of this procedure is to determine VE from coke oven door areas by carefully observing the door area from a standard distance while walking at a normal pace.
11.2.1Number of Runs. Refer to § 63.309(c)(1) of this part for the appropriate number of runs.
11.2.2Battery Traverse. To conduct a battery traverse, walk the length of the battery on the outside of the pusher machine and quench car tracks at a steady, normal walking pace, pausing to make appropriate entries on the door area inspection sheet (Figure 303-2). A single test run consists of two timed traverses, one for the coke side and one for the push side. The walking pace shall be such that the duration of the traverse does not exceed an average of 4 seconds per oven door, excluding time spent moving around stationary obstructions or waiting for other obstructions to move from positions blocking the view of a series of doors. Extra time is allowed for each leak (a maximum of 10 additional seconds for each leaking door) for the observer to make the proper notation. A walking pace of 3 seconds per oven door has been found to be typical. Record the actual traverse time with a stopwatch.
11.2.2.1Include in the traverse time only the time spent observing the doors and recording door leaks. To measure actual traverse time, use an accumulative-type stopwatch with unit divisions of 0.5 seconds or less. Exclude interruptions to the traverse and time required for the observer to move to positions where the view of the battery is unobstructed, or for obstructions, such as the door machine, to move from positions blocking the view of a series of doors.
11.2.2.2Various situations may arise that will prevent the observer from viewing a door or a series of doors. Prior to the door inspection, the owner or operator may elect to temporarily suspend charging operations for the duration of the inspection, so that all of the doors can be viewed by the observer. The observer has two options for dealing with obstructions to view: (a) Stop the stopwatch and wait for the equipment to move or the fugitive emissions to dissipate before completing the traverse; or (b) stop the stopwatch, skip the affected ovens, and move to an unobstructed position to continue the traverse. Restart the stopwatch and continue the traverse. After the completion of the traverse, if the equipment has moved or the fugitive emissions have dissipated, inspect the affected doors. If the equipment is still preventing the observer from viewing the doors, then the affected doors may be counted as not observed. If option (b) is used because of doors blocked by machines during charging operations, then, of the affected doors, exclude the door from the most recently charged oven from the inspection. Record the oven numbers and make an appropriate notation under “Comments” on the door area inspection sheet (Figure 303-2).
11.2.2.3When batteries have sheds to control emissions, conduct the inspection from outside the shed unless the doors cannot be adequately viewed. In this case, conduct the inspection from the bench. Be aware of special safety considerations pertinent to walking on the bench and follow the instructions of company personnel on the required equipment and procedures. If possible, conduct the bench traverse whenever the bench is clear of the door machine and hot coke guide.
11.2.3Observations. Record all the information requested at the top of the door area inspection sheet (Figure 303-2), including the number of non-operating ovens. Record the clock time at the start of the traverse on each side of the battery. Record which side is being inspected (i.e., coke side or push side). Other information may be recorded at the discretion of the observer, such as the location of the leak (e.g., top of the door, chuck door, etc.), the reason for any interruption of the traverse, or the position of the sun relative to the battery and sky conditions (e.g., overcast, partly sunny, etc.).
11.2.3.1Begin the test run by starting the stopwatch and traversing either the coke side or the push side of the battery. After completing one side, stop the watch. Complete this procedure on the other side. If inspecting more than one battery, the observer may view the push sides and the coke sides sequentially.
11.2.3.2During the traverse, look around the entire perimeter of each oven door. The door is considered leaking if VE are detected in the coke oven door area. The coke oven door area includes the entire area on the vertical face of a coke oven between the bench and the top of the battery between two adjacent buck stays (e.g., the oven door, chuck door, between the masonry brick, buck stay or jamb, or other sources). Record the oven number and make the appropriate notation on the door area inspection sheet (Figure 303-2).
Note:
Multiple VE from the same door area (e.g., VE from both the chuck door and the push side door) are counted as only one emitting door, not as multiple emitting doors.
11.2.3.3Do not record the following sources as door area VE:
11.2.3.3.1VE from ovens with doors removed. Record the oven number and make an appropriate notation under “Comments;”
11.2.3.3.2VE from ovens taken out of service. The owner or operator shall notify the observer as to which ovens are out of service. Record the oven number and make an appropriate notation under “Comments;” or
11.2.3.3.3VE from hot coke that has been spilled on the bench as a result of pushing.
11.2.4Criteria for Acceptance. After completing the run, calculate the maximum time allowed to observe the ovens using the equation in Section 12.2. If the total traverse time exceeds T, void the run, and conduct another run to satisfy the requirements of § 63.309(c)(1) of this part.
11.2.5Percent Leaking Doors. For each day on which a valid observation is obtained, calculate the daily 30-day rolling average for each battery using these data and the 29 previous valid daily observations, in accordance with Section 12.5.
11.3Procedure for Determining VE from Topside Port Lids and Offtake Systems.
11.3.1Number of Runs. Refer to § 63.309(c)(1) of this part for the number of runs to be conducted. Simultaneous runs or separate runs for the topside port lids and offtake systems may be conducted.
11.3.2Battery Traverse. To conduct a topside traverse of the battery, walk the length of the battery at a steady, normal walking pace, pausing only to make appropriate entries on the topside inspection sheet (Figure 303-3). The walking pace shall not exceed an average rate of 4 seconds per oven, excluding time spent moving around stationary obstructions or waiting for other obstructions to move from positions blocking the view. Extra time is allowed for each leak for the observer to make the proper notation. A walking pace of 3 seconds per oven is typical. Record the actual traverse time with a stopwatch.
11.3.3Topside Port Lid Observations. To observe lids of the ovens involved in the charging operation, the observer shall wait to view the lids until approximately 5 minutes after the completion of the charge. Record all the information requested on the topside inspection sheet (Figure 303-3). Record the clock time when traverses begin and end. If the observer's view is obstructed during the traverse (e.g., steam from the coke wharf, larry car, etc.), follow the guidelines given in Section 11.2.2.2.
11.3.3.1To perform a test run, conduct a single traverse on the topside of the battery. The observer shall walk near the center of the battery but may deviate from this path to avoid safety hazards (such as open or closed charging ports, luting buckets, lid removal bars, and topside port lids that have been removed) and any other obstacles. Upon noting VE from the topside port lid(s) of an oven, record the oven number and port number, then resume the traverse. If any oven is dampered-off from the collecting main for decarbonization, note this under “Comments” for that particular oven.
Note:
Count the number of topside ports, not the number of points, exhibiting VE, i.e., if a topside port has several points of VE, count this as one port exhibiting VE.
11.3.3.2Do not count the following as topside port lid VE:
11.3.3.2.1VE from between the brickwork and oven lid casing or VE from cracks in the oven brickwork. Note these VE under “Comments;”
11.3.3.2.2VE from topside ports involved in a charging operation. Record the oven number, and make an appropriate notation (e.g., not observed because ports open for charging) under “Comments;”
11.3.3.2.3Topside ports having maintenance work done. Record the oven number and make an appropriate notation under “Comments;” or
11.3.3.2.4Condensing water from wet-sealing material. Ports with only visible condensing water from wet-sealing material are counted as observed but not as having VE.
11.3.3.2.5Visible emissions from the flue inspection ports and caps.
11.3.4Offtake Systems Observations. To perform a test run, traverse the battery as in Section 11.3.3.1. Look ahead and back two to four ovens to get a clear view of the entire offtake system for each oven. Consider visible emissions from the following points as offtake system VE: (a) the flange between the gooseneck and collecting main (“saddle”), (b) the junction point of the standpipe and oven (“standpipe base”), (c) the other parts of the offtake system (e.g., the standpipe cap), and (d) the junction points with ovens and flanges of jumper pipes.
11.3.4.1Do not stray from the traverse line in order to get a “closer look” at any part of the offtake system unless it is to distinguish leaks from interferences from other sources or to avoid obstacles.
11.3.4.2If the centerline does not provide a clear view of the entire offtake system for each oven (e.g., when standpipes are longer than 15 feet), the observer may conduct the traverse farther from (rather than closer to) the offtake systems.
11.3.4.3Upon noting a leak from an offtake system during a traverse, record the oven number. Resume the traverse. If the oven is dampered-off from the collecting main for decarbonization and VE are observed, note this under “Comments” for that particular oven.
11.3.4.4If any part or parts of an offtake system have VE, count it as one emitting offtake system. Each stationary jumper pipe is considered a single offtake system.
11.3.4.5Do not count standpipe caps open for a decarbonization period or standpipes of an oven being charged as source of offtake system VE. Record the oven number and write “Not observed” and the reason (i.e., decarb or charging) under “Comments.”
Note:
VE from open standpipes of an oven being charged count as charging emissions. All VE from closed standpipe caps count as offtake leaks.
11.3.5Criteria for Acceptance. After completing the run (allow 2 traverses for batteries with double mains), calculate the maximum time allowed to observe the topside port lids and/or offtake systems using the equation in Section 12.3. If the total traverse time exceeds T, void the run and conduct another run to satisfy the requirements of § 63.309(c)(1) of this part.
11.3.6In determining the percent leaking topside port lids and percent leaking offtake systems, do not include topside port lids or offtake systems with VE from the following ovens:
11.3.6.1Empty ovens, including ovens undergoing maintenance, which are properly dampered off from the main.
11.3.6.2Ovens being charged or being pushed.
11.3.6.3Up to 3 full ovens that have been dampered off from the main prior to pushing.
11.3.6.4Up to 3 additional full ovens in the pushing sequence that have been dampered off from the main for offtake system cleaning, for decarbonization, for safety reasons, or when a charging/pushing schedule involves widely separated ovens (e.g., a Marquard system); or that have been dampered off from the main for maintenance near the end of the coking cycle. Examples of reasons that ovens are dampered off for safety reasons are to avoid exposing workers in areas with insufficient clearance between standpipes and the larry car, or in areas where workers could be exposed to flames or hot gases from open standpipes, and to avoid the potential for removing a door on an oven that is not dampered off from the main.
11.3.7Percent Leaking Topside Port Lids and Offtake Systems. For each day on which a valid observation is obtained, calculate the daily 30-day rolling average for each battery using these data and the 29 previous valid daily observations, in accordance with Sections 12.6 and 12.7.
11.4Procedure for Determining VE from Collecting Mains.
11.4.1Traverse. To perform a test run, traverse both the collecting main catwalk and the battery topside along the side closest to the collecting main. If the battery has a double main, conduct two sets of traverses for each run, i.e., one set for each main.
11.4.2Data Recording. Upon noting VE from any portion of a collection main, identify the source and approximate location of the source of VE and record the time under “Collecting main” on Figure 303-3; then resume the traverse.
11.4.3Collecting Main Pressure Check. After the completion of the door traverse, the topside port lids, and offtake systems, compare the collecting main pressure during the inspection to the collecting main pressure during the previous 8 to 24 hours. Record the following: (a) the pressure during inspection, (b) presence of pressure deviation from normal operations, and (c) the explanation for any pressure deviation from normal operations, if any, offered by the operators. The owner or operator of the coke battery shall maintain the pressure recording equipment and conduct the quality assurance/quality control (QA/QC) necessary to ensure reliable pressure readings and shall keep the QA/QC records for at least 6 months. The observer may periodically check the QA/QC records to determine their completeness. The owner or operator shall provide access to the records within 1 hour of an observer's request.
12.0Data Analysis and Calculations
12.1Nomenclature.
A = 150 or the number of valid observations (runs). The value of A shall not be less than 145, except for purposes of determinations under § 63.306(c) (work practice plan implementation) or § 63.306(d) (work practice plan revisions) of this part. No set of observations shall be considered valid for such a recalculation that otherwise would not be considered a valid set of observations for a calculation under this paragraph.
Di = Number of doors on non-operating ovens.
Dno = Number of doors not observed.
Dob = Total number of doors observed on operating ovens.
Dt = Total number of oven doors on the battery.
e = 2.72
J = Number of stationary jumper pipes.
L = Number of doors with VE.
Lb = Yard-equivalent reading.
Ls = Number of doors with VE observed from the bench under sheds.
Ly = Number of doors with VE observed from the yard.
Ly = Number of doors with VE observed from the yard on the push side.
ln = Natural logarithm.
N = Total number of ovens in the battery.
Ni = Total number of inoperable ovens.
PNO = Number of ports not observed.
Povn = Number of ports per oven.
PVE = Number of topside port lids with VE.
PLD = Percent leaking coke oven doors for the test run.
PLL = Percent leaking topside port lids for the run.
PLO = Percent leaking offtake systems.
T = Total time allowed for traverse, seconds.
Tovn = Number of offtake systems (excluding jumper pipes) per oven.
TNO = Number of offtake systems not observed.
TVE = Number of offtake systems with VE.
Xi = Seconds of VE during the ith charge.
Z = Number of topside port lids or offtake systems with VE.
12.2Criteria for Acceptance for VE Determinations from Coke Oven Door Areas. After completing the run, calculate the maximum time allowed to observe the ovens using the following equation:
12.3Criteria for Acceptance for VE Determinations from Topside Port Lids and Offtake Systems. After completing the run (allow 2 traverses for batteries with double mains), calculate the maximum time allowed to observe the topside port lids and/or offtake systems by the following equation:
12.4Average Duration of VE from Charging Operations. Use Equation 303-3 to calculate the daily 30-day rolling log average of seconds of visible emissions from the charging operation for each battery using these current day's observations and the 29 previous valid daily sets of observations.
12.5Percent Leaking Doors (PLD). Determine the total number of doors for which observations were made on the coke oven battery as follows:
12.5.1For each test run (one run includes both the coke side and the push side traverses), sum the number of doors with door area VE. For batteries subject to an approved alternative standard under § 63.305 of this part, calculate the push side and the coke side PLD separately.
12.5.2Calculate percent leaking doors by using Equation 303-5:
12.5.3When traverses are conducted from the bench under sheds, calculate the coke side and the push side separately. Use Equation 303-6 to calculate a yard-equivalent reading:
If Lb is less than zero, use zero for Lb in Equation 303-7 in the calculation of PLD.
12.5.3.1Use Equation 303-7 to calculate PLD:
Round off PLD to the nearest hundredth of 1 percent and record as the percent leaking coke oven doors for the run.
12.5.3.2Average Percent Leaking Doors. Use Equation 303-8 to calculate the daily 30-day rolling average percent leaking doors for each battery using these current day's observations and the 29 previous valid daily sets of observations.
12.6Topside Port Lids. Determine the percent leaking topside port lids for each run as follows:
12.6.1Round off this percentage to the nearest hundredth of 1 percent and record this percentage as the percent leaking topside port lids for the run.
12.6.2Average Percent Leaking Topside Port Lids. Use Equation 303-10 to calculate the daily 30-day rolling average percent leaking topside port lids for each battery using these current day's observations and the 29 previous valid daily sets of observations.
12.7Offtake Systems. Determine the percent leaking offtake systems for the run as follows:
12.7.1Round off this percentage to the nearest hundredth of 1 percent and record this percentage as the percent leaking offtake systems for the run.
12.7.2Average Percent Leaking Offtake Systems. Use Equation 303-12 to calculate the daily 30-day rolling average percent leaking offtake systems for each battery using these current day's observations and the 29 previous valid daily sets of observations.
13.0Method Performance [Reserved]
14.0Pollution Prevention [Reserved]
15.0Waste Management [Reserved]
16.0References.
1. Missan, R., and A. Stein. Guidelines for Evaluation of Visible Emissions Certification, Field Procedures, Legal Aspects, and Background Material. U.S. Environmental Protection Agency. EPA Publication No. EPA-340/1-75-007. April 1975.
2. Wohlschlegel, P., and D. E. Wagoner. Guideline for Development of a Quality Assurance Program: Volume IX—Visual Determination of Opacity Emission from Stationary Sources. U.S. Environmental Protection Agency. EPA Publication No. EPA-650/4-74-005i. November 1975.
3. U.S. Occupational Safety and Health Administration. Code of Federal Regulations. Title 29, Chapter XVII, Section 1910.1029(g). Washington, D.C. Government Printing Office. July 1, 1990.
4. U.S. Environmental Protection Agency. National Emission Standards for Hazardous Air Pollutants; Coke Oven Emissions from Wet-Coal Charged By-Product Coke Oven Batteries; Proposed Rule and Notice of Public Hearing. Washington, D.C. Federal Register. Vol. 52, No. 78 (13586). April 23, 1987.
17.0Tables, Diagrams, Flowcharts, and Validation Data
Company name:
Battery no.: ___ Date: ___ Run no.: ___
City, State:
Observer name:
Company representative(s):
Charge No. OvenNo. Clock time Visibleemissions, seconds Comments
Figure 303-1. Charging System Inspection
Company name:
Battery no.:
Date:
City, State:
Total no. of ovens in battery:
Observer name:
Certification expiration date:
Inoperable ovens:
Company representative(s):
Traverse time CS:
Traverse time PS:
Valid run (Y or N):
Time traverse started/completed PS/CS Door No. Comments(No. of blocked doors, interruptions to traverse, etc.)
Figure 303-2. Door Area Inspection.
Company name:
Battery no.:
Date:
City, State:
Total no. of ovens in battery:
Observer name:
Certification expiration date:
Inoperable ovens:
Company representative(s):
Total no. of lids:
Total no. of offtakes:
Total no. of jumper pipes:
Ovens not observed:
Total traverse time:
Valid run (Y or N):
Time traverse started/completed Type of Inspection(lids, offtakes, collecting main) Location of VE(Oven #/Port #) Comments
Figure 303-3. Topside Inspection
Method 303A—Determination of Visible Emissions From Nonrecovery Coke Oven Batteries
Note:
This method does not include all of the specifications pertaining to observer certification. Some material is incorporated by reference from other methods in this part and in appendix A to 40 CFR part 60. Therefore, to obtain reliable results, persons using this method should have a thorough knowledge of Method 9 and Method 303.
1.0Scope and Application
1.1Applicability. This method is applicable for the determination of visible emissions (VE) from leaking doors at nonrecovery coke oven batteries.
2.0Summary of Method
2.1A certified observer visually determines the VE from coke oven battery sources while walking at a normal pace. This method does not require that opacity of emissions be determined or that magnitude be differentiated.
3.0Definitions
3.1Bench means the platform structure in front of the oven doors.
3.2Coke oven door means each end enclosure on the push side and the coking side of an oven.
3.3Coke side means the side of a battery from which the coke is discharged from ovens at the end of the coking cycle.
3.4Nonrecovery coke oven battery means a source consisting of a group of ovens connected by common walls and operated as a unit, where coal undergoes destructive distillation under negative pressure to produce coke, and which is designed for the combustion of coke oven gas from which by-products are not recovered.
3.5Operating oven means any oven not out of operation for rebuild or maintenance work extensive enough to require the oven to be skipped in the charging sequence.
3.6Oven means a chamber in the coke oven battery in which coal undergoes destructive distillation to produce coke.
3.7Push side means the side of the battery from which the coke is pushed from ovens at the end of the coking cycle.
3.8Run means the observation of visible emissions from coke oven doors in accordance with this method.
3.9Shed means an enclosure that covers the side of the coke oven battery, captures emissions from pushing operations and from leaking coke oven doors on the coke side or push side of the coke oven battery, and routes the emissions to a control device or system.
3.10Traverse time means accumulated time for a traverse as measured by a stopwatch. Traverse time includes time to stop and write down oven numbers but excludes time waiting for obstructions of view to clear or for time to walk around obstacles.
3.11Visible Emissions or VE means any emission seen by the unaided (except for corrective lenses) eye, excluding steam or condensing water.
4.0Interferences [Reserved]
5.0Safety
5.1Disclaimer. This method may involve hazardous materials, operations, and equipment. This test method may not address all of the safety problems associated with its use. It is the responsibility of the user of this test method to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to performing this test method.
5.2Safety Training. Because coke oven batteries have hazardous environments, the training materials and the field training (Section 10.0) shall cover the precautions required by the company to address health and safety hazards. Special emphasis shall be given to the Occupational Safety and Health Administration (OSHA) regulations pertaining to exposure of coke oven workers (see Reference 3 in Section 16.0). In general, the regulation requires that special fire-retardant clothing and respirators be worn in certain restricted areas of the coke oven battery. The OSHA regulation also prohibits certain activities, such as chewing gum, smoking, and eating in these areas.
6.0Equipment and Supplies [Reserved]
7.0Reagents and Standards [Reserved]
8.0Sample Collection, Preservation, Transport, and Storage [Reserved]
9.0Quality Control [Reserved]
10.0Calibration and Standardization.
10.1Training. This method requires only the determination of whether VE occur and does not require the determination of opacity levels; therefore, observer certification according to Method 9 in appendix A to part 60 is not required. However, the first-time observer (trainee) shall have attended the lecture portion of the Method 9 certification course. Furthermore, before conducting any VE observations, an observer shall become familiar with nonrecovery coke oven battery operations and with this test method by observing for a minimum of 4 hours the operation of a nonrecovery coke oven battery in the presence of personnel experienced in performing Method 303 assessments.
11.0Procedure
The intent of this procedure is to determine VE from coke oven door areas by carefully observing the door area while walking at a normal pace.
11.1Number of Runs. Refer to § 63.309(c)(1) of this part for the appropriate number of runs.
11.2Battery Traverse. To conduct a battery traverse, walk the length of the battery on the outside of the pusher machine and quench car tracks at a steady, normal walking pace, pausing to make appropriate entries on the door area inspection sheet (Figure 303A-1). The walking pace shall be such that the duration of the traverse does not exceed an average of 4 seconds per oven door, excluding time spent moving around stationary obstructions or waiting for other obstructions to move from positions blocking the view of a series of doors. Extra time is allowed for each leak (a maximum of 10 additional seconds for each leaking door) for the observer to make the proper notation. A walking pace of 3 seconds per oven door has been found to be typical. Record the actual traverse time with a stopwatch. A single test run consists of two timed traverses, one for the coke side and one for the push side.
11.2.1Various situations may arise that will prevent the observer from viewing a door or a series of doors. The observer has two options for dealing with obstructions to view: (a) Wait for the equipment to move or the fugitive emissions to dissipate before completing the traverse; or (b) skip the affected ovens and move to an unobstructed position to continue the traverse. Continue the traverse. After the completion of the traverse, if the equipment has moved or the fugitive emissions have dissipated, complete the traverse by inspecting the affected doors. Record the oven numbers and make an appropriate notation under “Comments” on the door area inspection sheet (Figure 303A-1).
Note:
Extra time incurred for handling obstructions is not counted in the traverse time.
11.2.2When batteries have sheds to control pushing emissions, conduct the inspection from outside the shed, if the shed allows such observations, or from the bench. Be aware of special safety considerations pertinent to walking on the bench and follow the instructions of company personnel on the required equipment and operations procedures. If possible, conduct the bench traverse whenever the bench is clear of the door machine and hot coke guide.
11.3Observations. Record all the information requested at the top of the door area inspection sheet (Figure 303A-1), including the number of non-operating ovens. Record which side is being inspected, i.e., coke side or push side. Other information may be recorded at the discretion of the observer, such as the location of the leak (e.g., top of the door), the reason for any interruption of the traverse, or the position of the sun relative to the battery and sky conditions (e.g., overcast, partly sunny, etc.).
11.3.1Begin the test run by traversing either the coke side or the push side of the battery. After completing one side, traverse the other side.
11.3.2During the traverse, look around the entire perimeter of each oven door. The door is considered leaking if VE are detected in the coke oven door area. The coke oven door area includes the entire area on the vertical face of a coke oven between the bench and the top of the battery and the adjacent doors on both sides. Record the oven number and make the appropriate notation on the door area inspection sheet (Figure 303A-1).
11.3.3Do not record the following sources as door area VE:
11.3.3.1VE from ovens with doors removed. Record the oven number and make an appropriate notation under “Comments”;
11.3.3.2VE from ovens where maintenance work is being conducted. Record the oven number and make an appropriate notation under “Comments”; or
11.3.3.3VE from hot coke that has been spilled on the bench as a result of pushing.
12.0Data Analysis and Calculations
Same as Method 303, Section 12.1, 12.2, 12.3, 12.4, and 12.5.
13.0Method Performance [Reserved]
14.0Pollution Prevention [Reserved]
15.0Waste Management [Reserved]
16.0References
Same as Method 303, Section 16.0.
17.0Tables, Diagrams, Flowcharts, and Validation Data
Company name:
Battery no.:
Date:
City, State:
Total no. of ovens in battery:
Observer name:
Certification expiration date:
Inoperable ovens:
Company representative(s):
Traverse time CS:
Traverse time PS:
Valid run (Y or N):
Time traverse started/completed PS/CS Door No. Comments(No. of blocked doors, interruptions to traverse, etc.)
Figure 303A-1. Door Area Inspection
Method 304A: Determination of Biodegradation Rates of Organic Compounds (Vent Option)
1.0Scope and Application
1.1Applicability. This method is applicable for the determination of biodegradation rates of organic compounds in an activated sludge process. The test method is designed to evaluate the ability of an aerobic biological reaction system to degrade or destroy specific components in waste streams. The method may also be used to determine the effects of changes in wastewater composition on operation. The biodegradation rates determined by utilizing this method are not representative of a full-scale system. The rates measured by this method shall be used in conjunction with the procedures listed in appendix C of this part to calculate the fraction emitted to the air versus the fraction biodegraded.
2.0Summary of Method
2.1A self-contained benchtop bioreactor system is assembled in the laboratory. A sample of mixed liquor is added and the waste stream is then fed continuously. The benchtop bioreactor is operated under conditions nearly identical to the target full-scale activated sludge process. Bioreactor temperature, dissolved oxygen concentration, average residence time in the reactor, waste composition, biomass concentration, and biomass composition of the full-scale process are the parameters which are duplicated in the benchtop bioreactor. Biomass shall be removed from the target full-scale activated sludge unit and held for no more than 4 hours prior to use in the benchtop bioreactor. If antifoaming agents are used in the full-scale system, they shall also be used in the benchtop bioreactor. The feed flowing into and the effluent exiting the benchtop bioreactor are analyzed to determine the biodegradation rates of the target compounds. The flow rate of the exit vent is used to calculate the concentration of target compounds (utilizing Henry's law) in the exit gas stream. If Henry's law constants for the compounds of interest are not known, this method cannot be used in the determination of the biodegradation rate and Method 304B is the suggested method. The choice of analytical methodology for measuring the compounds of interest at the inlet and outlet to the benchtop bioreactor are left to the discretion of the source, except where validated methods are available.
3.0Definitions [Reserved]
4.0Interferences [Reserved]
5.0Safety
5.1If explosive gases are produced as a byproduct of biodegradation and could realistically pose a hazard, closely monitor headspace concentration of these gases to ensure laboratory safety. Placement of the benchtop bioreactor system inside a laboratory hood is recommended regardless of byproducts produced.
6.0.Equipment and Supplies
Note:
Figure 304A-1 illustrates a typical laboratory apparatus used to measure biodegradation rates. While the following description refers to Figure 304A-1, the EPA recognizes that alternative reactor configurations, such as alternative reactor shapes and locations of probes and the feed inlet, will also meet the intent of this method. Ensure that the benchtop bioreactor system is self-contained and isolated from the atmosphere (except for the exit vent stream) by leak-checking fittings, tubing, etc.
6.1Benchtop Bioreactor. The biological reaction is conducted in a biological oxidation reactor of at least 6 liters capacity. The benchtop bioreactor is sealed and equipped with internal probes for controlling and monitoring dissolved oxygen and internal temperature. The top of the reactor is equipped for aerators, gas flow ports, and instrumentation (while ensuring that no leaks to the atmosphere exist around the fittings).
6.2Aeration gas. Aeration gas is added to the benchtop bioreactor through three diffusers, which are glass tubes that extend to the bottom fifth of the reactor depth. A pure oxygen pressurized cylinder is recommended in order to maintain the specified oxygen concentration. Install a blower (e.g., Diaphragm Type, 15 SCFH capacity) to blow the aeration gas into the reactor diffusers. Measure the aeration gas flow rate with a rotameter (e.g., 0-15 SCFH recommended). The aeration gas will rise through the benchtop bioreactor, dissolving oxygen into the mixture in the process. The aeration gas must provide sufficient agitation to keep the solids in suspension. Provide an exit for the aeration gas from the top flange of the benchtop bioreactor through a water-cooled (e.g., Allihn-type) vertical condenser. Install the condenser through a gas-tight fitting in the benchtop bioreactor closure. Install a splitter which directs a portion of the gas to an exit vent and the rest of the gas through an air recycle pump back to the benchtop bioreactor. Monitor and record the flow rate through the exit vent at least 3 times per day throughout the day.
6.3Wastewater Feed. Supply the wastewater feed to the benchtop bioreactor in a collapsible low-density polyethylene container or collapsible liner in a container (e.g., 20 L) equipped with a spigot cap (collapsible containers or liners of other material may be required due to the permeability of some volatile compounds through polyethylene). Obtain the wastewater feed by sampling the wastewater feed in the target process. A representative sample of wastewater shall be obtained from the piping leading to the aeration tank. This sample may be obtained from existing sampling valves at the discharge of the wastewater feed pump, or collected from a pipe discharging to the aeration tank, or by pumping from a well-mixed equalization tank upstream from the aeration tank. Alternatively, wastewater can be pumped continuously to the laboratory apparatus from a bleed stream taken from the equalization tank of the full-scale treatment system.
6.3.1Refrigeration System. Keep the wastewater feed cool by ice or by refrigeration to 4 °C. If using a bleed stream from the equalization tank, refrigeration is not required if the residence time in the bleed stream is less than five minutes.
6.3.2Wastewater Feed Pump. The wastewater is pumped from the refrigerated container using a variable-speed peristaltic pump drive equipped with a peristaltic pump head. Add the feed solution to the benchtop bioreactor through a fitting on the top flange. Determine the rate of feed addition to provide a retention time in the benchtop bioreactor that is numerically equivalent to the retention time in the full-scale system. The wastewater shall be fed at a rate sufficient to achieve 90 to 100 percent of the full-scale system residence time.
6.3.3Treated wastewater feed. The benchtop bioreactor effluent exits at the bottom of the reactor through a tube and proceeds to the clarifier.
6.4Clarifier. The effluent flows to a separate closed clarifier that allows separation of biomass and effluent (e.g., 2-liter pear-shaped glass separatory funnel, modified by removing the stopcock and adding a 25-mm OD glass tube at the bottom). Benchtop bioreactor effluent enters the clarifier through a tube inserted to a depth of 0.08 m (3 in.) through a stopper at the top of the clarifier. System effluent flows from a tube inserted through the stopper at the top of the clarifier to a drain (or sample bottle when sampling). The underflow from the clarifier leaves from the glass tube at the bottom of the clarifier. Flexible tubing connects this fitting to the sludge recycle pump. This pump is coupled to a variable speed pump drive. The discharge from this pump is returned through a tube inserted in a port on the side of the benchtop bioreactor. An additional port is provided near the bottom of the benchtop bioreactor for sampling the reactor contents. The mixed liquor from the benchtop bioreactor flows into the center of the clarifier. The clarified system effluent separates from the biomass and flows through an exit near the top of the clarifier. There shall be no headspace in the clarifier.
6.5Temperature Control Apparatus. Capable of maintaining the system at a temperature equal to the temperature of the full-scale system. The average temperature should be maintained within ±2 °C of the set point.
6.5.1Temperature Monitoring Device. A resistance type temperature probe or a thermocouple connected to a temperature readout with a resolution of 0.1 °C or better.
6.5.2Benchtop Bioreactor Heater. The heater is connected to the temperature control device.
6.6Oxygen Control System. Maintain the dissolved oxygen concentration at the levels present in the full-scale system. Target full-scale activated sludge systems with dissolved oxygen concentration below 2 mg/L are required to maintain the dissolved oxygen concentration in the benchtop ioreactor within 0.5 mg/L of the target dissolved oxygen level. Target full-scale activated sludge systems with dissolved oxygen concentration above 2 mg/L are required to maintain the dissolved oxygen concentration in the benchtop bioreactor within 1.5 mg/L of the target dissolved oxygen concentration; however, for target full-scale activated sludge systems with dissolved oxygen concentrations above 2 mg/L, the dissolved oxygen concentration in the benchtop bioreactor may not drop below 1.5 mg/L. If the benchtop bioreactor is outside the control range, the dissolved oxygen is noted and the reactor operation is adjusted.
6.6.1Dissolved Oxygen Monitor. Dissolved oxygen is monitored with a polarographic probe (gas permeable membrane) connected to a dissolved oxygen meter (e.g., 0 to 15 mg/L, 0 to 50 °C).
6.6.2Benchtop Bioreactor Pressure Monitor. The benchtop bioreactor pressure is monitored through a port in the top flange of the reactor. This is connected to a gauge control with a span of 13-cm water vacuum to 13-cm water pressure or better. A relay is activated when the vacuum exceeds an adjustable setpoint which opens a solenoid valve (normally closed), admitting oxygen to the system. The vacuum setpoint controlling oxygen addition to the system shall be set at approximately 2.5 ±0.5 cm water and maintained at this setting except during brief periods when the dissolved oxygen concentration is adjusted.
6.7Connecting Tubing. All connecting tubing shall be Teflon or equivalent in impermeability. The only exception to this specification is the tubing directly inside the pump head of the wastewater feed pump, which may be Viton, Silicone or another type of flexible tubing.
Note:
Mention of trade names or products does not constitute endorsement by the U.S. Environmental Protection Agency.
7.0Reagents and Standards
7.1Wastewater. Obtain a representative sample of wastewater at the inlet to the full-scale treatment plant if there is an existing full-scale treatment plant (see section 6.3). If there is no existing full-scale treatment plant, obtain the wastewater sample as close to the point of determination as possible. Collect the sample by pumping the wastewater into the 20-L collapsible container. The loss of volatiles shall be minimized from the wastewater by collapsing the container before filling, by minimizing the time of filling, and by avoiding a headspace in the container after filling. If the wastewater requires the addition of nutrients to support the biomass growth and maintain biomass characteristics, those nutrients are added and mixed with the container contents after the container is filled.
7.2Biomass. Obtain the biomass or activated sludge used for rate constant determination in the bench-scale process from the existing full-scale process or from a representative biomass culture (e.g., biomass that has been developed for a future full-scale process). This biomass is preferentially obtained from a thickened acclimated mixed liquor sample. Collect the sample either by bailing from the mixed liquor in the aeration tank with a weighted container, or by collecting aeration tank effluent at the effluent overflow weir. Transport the sample to the laboratory within no more than 4 hours of collection. Maintain the biomass concentration in the benchtop bioreactor at the level of the full-scale system 10 percent throughout the sampling period of the test method.
8.0Sample Collection, Preservation, Storage, and Transport
8.1Benchtop Bioreactor Operation. Charge the mixed liquor to the benchtop bioreactor, minimizing headspace over the liquid surface to minimize entrainment of mixed liquor in the circulating gas. Fasten the benchtop bioreactor headplate to the reactor over the liquid surface. Maintain the temperature of the contents of the benchtop bioreactor system at the temperature of the target full-scale system, ±2 °C, throughout the testing period. Monitor and record the temperature of the benchtop bioreactor contents at least to the nearest 0.1 °C.
8.1.1Wastewater Storage. Collect the wastewater sample in the 20-L collapsible container. Store the container at 4 °C throughout the testing period. Connect the container to the benchtop bioreactor feed pump.
8.1.2Wastewater Flow Rate.
8.1.2.1The hydraulic residence time of the aeration tank is calculated as the ratio of the volume of the tank (L) to the flow rate (L/min). At the beginning of a test, the container shall be connected to the feed pump and solution shall be pumped to the benchtop bioreactor at the required flow rate to achieve the calculated hydraulic residence time of wastewater in the aeration tank.
Where:
Qtest = wastewater flow rate (L/min)
Qfs = average flow rate of full-scale process (L/min)
Vfs = volume of full-scale aeration tank (L)
8.1.2.2The target flow rate in the test apparatus is the same as the flow rate in the target full-scale process multiplied by the ratio of benchtop bioreactor volume (e.g., 6 L) to the volume of the full-scale aeration tank. The hydraulic residence time shall be maintained at 90 to 100 percent of the residence time maintained in the full-scale unit. A nominal flow rate is set on the pump based on a pump calibration. Changes in the elasticity of the tubing in the pump head and the accumulation of material in the tubing affect this calibration. The nominal pumping rate shall be changed as necessary based on volumetric flow measurements. Discharge the benchtop bioreactor effluent to a wastewater storage, treatment, or disposal facility, except during sampling or flow measurement periods.
8.1.3Sludge Recycle Rate. Set the sludge recycle rate at a rate sufficient to prevent accumulation in the bottom of the clarifier. Set the air circulation rate sufficient to maintain the biomass in suspension.
8.1.4Benchtop Bioreactor Operation and Maintenance. Temperature, dissolved oxygen concentration, exit vent flow rate, benchtop bioreactor effluent flow rate, and air circulation rate shall be measured and recorded three times throughout each day of benchtop bioreactor operation. If other parameters (such as pH) are measured and maintained in the target full-scale unit, these parameters, where appropriate, shall be monitored and maintained to target full-scale specifications in the benchtop bioreactor. At the beginning of each sampling period (Section 8.2), sample the benchtop bioreactor contents for suspended solids analysis. Take this sample by loosening a clamp on a length of tubing attached to the lower side port. Determine the suspended solids gravimetrically by the Gooch crucible/glass fiber filter method for total suspended solids, in accordance with Standard Methods3 or equivalent. When necessary, sludge shall be wasted from the lower side port of the benchtop bioreactor, and the volume that is wasted shall be replaced with an equal volume of the reactor effluent. Add thickened activated sludge mixed liquor as necessary to the benchtop bioreactor to increase the suspended solids concentration to the desired level. Pump this mixed liquor to the benchtop bioreactor through the upper side port (Item 24 in Figure 304A-1). Change the membrane on the dissolved oxygen probe before starting the test. Calibrate the oxygen probe immediately before the start of the test and each time the membrane is changed.
8.1.5Inspection and Correction Procedures. If the feed line tubing becomes clogged, replace with new tubing. If the feed flow rate is not within 5 percent of target flow any time the flow rate is measured, reset pump or check the flow measuring device and measure flow rate again until target flow rate is achieved.
8.2Test Sampling. At least two and one half hydraulic residence times after the system has reached the targeted specifications shall be permitted to elapse before the first sample is taken. Effluent samples of the clarifier discharge (Item 20 in Figure 304A-1) and the influent wastewater feed are collected in 40-mL septum vials to which two drops of 1:10 hydrochloric acid (HCl) in water have been added. Sample the clarifier discharge directly from the drain line. These samples will be composed of the entire flow from the system for a period of several minutes. Feed samples shall be taken from the feed pump suction line after temporarily stopping the benchtop bioreactor feed, removing a connector, and squeezing the collapsible feed container. Store both influent and effluent samples at 4 °C immediately after collection and analyze within 8 hours of collection.
8.2.1Frequency of Sampling. During the test, sample and analyze the wastewater feed and the clarifier effluent at least six times. The sampling intervals shall be separated by at least 8 hours. During any individual sampling interval, sample the wastewater feed simultaneously with or immediately after the effluent sample. Calculate the relative standard deviation (RSD) of the amount removed (i.e., effluent concentration—wastewater feed concentration). The RSD values shall be < 15 percent. If an RSD value is > 15 percent, continue sampling and analyzing influent and effluent sets of samples until the RSD values are within specifications.
8.2.2Sampling After Exposure of System to Atmosphere. If, after starting sampling procedures, the benchtop bioreactor system is exposed to the atmosphere (due to leaks, maintenance, etc.), allow at least one hydraulic residence time to elapse before resuming sampling.
9.0Quality Control
9.1Dissolved Oxygen. Fluctuation in dissolved oxygen concentration may occur for numerous reasons, including undetected gas leaks, increases and decreases in mixed liquor suspended solids resulting from cell growth and solids loss in the effluent stream, changes in diffuser performance, cycling of effluent flow rate, and overcorrection due to faulty or sluggish dissolved oxygen probe response. Control the dissolved oxygen concentration in the benchtop bioreactor by changing the proportion of oxygen in the circulating aeration gas. Should the dissolved oxygen concentration drift below the designated experimental condition, bleed a small amount of aeration gas from the system on the pressure side (i.e., immediately upstream of one of the diffusers). This will create a vacuum in the system, triggering the pressure sensitive relay to open the solenoid valve and admit oxygen to the system. Should the dissolved oxygen concentration drift above the designated experimental condition, slow or stop the oxygen input to the system until the dissolved oxygen concentration approaches the correct level.
9.2Sludge Wasting.
9.2.1Determine the suspended solids concentration (section 8.1.4) at the beginning of a test, and once per day thereafter during the test. If the test is completed within a two day period, determine the suspended solids concentration after the final sample set is taken. If the suspended solids concentration exceeds the specified concentration, remove a fraction of the sludge from the benchtop bioreactor. The required volume of mixed liquor to remove is determined as follows:
Where:
Vw is the wasted volume (Liters),
Vr is the volume of the benchtop bioreactor (Liters),
Sm is the measured solids (g/L), and
Ss is the specified solids (g/L).
9.2.2Remove the mixed liquor from the benchtop bioreactor by loosening a clamp on the mixed liquor sampling tube and allowing the required volume to drain to a graduated flask. Clamp the tube when the correct volume has been wasted. Replace the volume of the liquid wasted by pouring the same volume of effluent back into the benchtop bioreactor. Dispose of the waste sludge properly.
9.3Sludge Makeup. In the event that the suspended solids concentration is lower than the specifications, add makeup sludge back into the benchtop bioreactor. Determine the amount of sludge added by the following equation:
Where:
Vw is the volume of sludge to add (Liters),
Vr is the volume of the benchtop bioreactor (Liters),
Sw is the solids in the makeup sludge (g/L),
Sm is the measured solids (g/L), and Ss is the specified solids (g/L).
10.0Calibration and Standardization
10.1Wastewater Pump Calibration. Determine the wastewater flow rate by collecting the system effluent for a time period of at least one hour, and measuring the volume with a graduated cylinder. Record the collection time period and volume collected. Determine flow rate. Adjust the pump speed to deliver the specified flow rate.
10.2Calibration Standards. Prepare calibration standards from pure certified standards in an aqueous medium. Prepare and analyze three concentrations of calibration standards for each target component (or for a mixture of components) in triplicate daily throughout the analyses of the test samples. At each concentration level, a single calibration shall be within 5 percent of the average of the three calibration results. The low and medium calibration standards shall bracket the expected concentration of the effluent (treated) wastewater. The medium and high standards shall bracket the expected influent concentration.
11.0Analytical Procedures
11.1Analysis. If the identity of the compounds of interest in the wastewater is not known, a representative sample of the wastewater shall be analyzed in order to identify all of the compounds of interest present. A gas chromatography/mass spectrometry screening method is recommended.
11.1.1After identifying the compounds of interest in the wastewater, develop and/or use one or more analytical techniques capable of measuring each of those compounds (more than one analytical technique may be required, depending on the characteristics of the wastewater). Test Method 18, found in appendix A of 40 CFR 60, may be used as a guideline in developing the analytical technique. Purge and trap techniques may be used for analysis providing the target components are sufficiently volatile to make this technique appropriate. The limit of quantitation for each compound shall be determined (see reference 1). If the effluent concentration of any target compound is below the limit of quantitation determined for that compound, the operation of the Method 304 unit may be altered to attempt to increase the effluent concentration above the limit of quantitation. Modifications to the method shall be approved prior to the test. The request should be addressed to Method 304 contact, Emissions Measurement Center, Mail Drop 19, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711.
12.0Data Analysis and Calculations
12.1Nomenclature. The following symbols are used in the calculations.
Ci = Average inlet feed concentration for a compound of interest, as analyzed (mg/L)
Co = Average outlet (effluent) concentration for a compound of interest, as analyzed (mg/L)
X = Biomass concentration, mixed liquor suspended solids (g/L)
t = Hydraulic residence time in the benchtop bioreactor (hours)
V = Volume of the benchtop bioreactor (L)
Q = Flow rate of wastewater into the benchtop bioreactor, average (L/hour)
12.2Residence Time. The hydraulic residence time of the benchtop bioreactor is equal to the ratio of the volume of the benchtop bioreactor (L) to the flow rate (L/h):
12.3Rate of Biodegradation. Calculate the rate of biodegradation for each component with the following equation:
12.4First-Order Biorate Constant. Calculate the first-order biorate constant (K1) for each component with the following equation:
12.5Relative Standard Deviation (RSD). Determine the standard deviation of both the influent and effluent sample concentrations (S) using the following equation:
12.6Determination of Percent Air Emissions and Percent Biodegraded. Use the results from this test method and follow the applicable procedures in appendix C of 40 CFR part 63, entitled, “Determination of the Fraction Biodegraded (Fbio) in a Biological Treatment Unit” to determine Fbio.
13.0Method Performance [Reserved]
14.0Pollution Prevention [Reserved]
15.0Waste Management [Reserved]
16.0References
1. “Guidelines for data acquisition and data quality evaluation in Environmental Chemistry,” Daniel MacDoughal, Analytical Chemistry, Volume 52, p. 2242, 1980.
2. Test Method 18, 40 CFR 60, appendix A.
3. Standard Methods for the Examination of Water and Wastewater, 16th Edition, Method 209C, Total Suspended Solids Dried at 103-105 °C, APHA, 1985.
4. Water7, Hazardous Waste Treatment, Storage, and Disposal Facilities (TSDF)—Air Emission Models, U.S. Environmental Protection Agency, EPA-450/3-87-026, Review Draft, November 1989.
5. Chemdat7, Hazardous Waste Treatment, Storage, and Disposal Facilities (TSDF)—Air Emission Models, U.S. Environmental Protection Agency, EPA-450/3-87-026, Review Draft, November 1989.
17.0Tables, Diagrams, Flowcharts, and Validation Data
Method 304B: Determination of Biodegradation Rates of Organic Compounds (Scrubber Option)
1.0Scope and Application
1.1Applicability. This method is applicable for the determination of biodegradation rates of organic compounds in an activated sludge process. The test method is designed to evaluate the ability of an aerobic biological reaction system to degrade or destroy specific components in waste streams. The method may also be used to determine the effects of changes in wastewater composition on operation. The biodegradation rates determined by utilizing this method are not representative of a full-scale system. Full-scale systems embody biodegradation and air emissions in competing reactions. This method measures biodegradation in absence of air emissions. The rates measured by this method shall be used in conjunction with the procedures listed in appendix C of this part to calculate the fraction emitted to the air versus the fraction biodegraded.
2.0Summary of Method
2.1A self-contained benchtop bioreactor system is assembled in the laboratory. A sample of mixed liquor is added and the waste stream is then fed continuously. The benchtop bioreactor is operated under conditions nearly identical to the target full-scale activated sludge process, except that air emissions are not a factor. The benchtop bioreactor temperature, dissolved oxygen concentration, average residence time in the reactor, waste composition, biomass concentration, and biomass composition of the target full-scale process are the parameters which are duplicated in the laboratory system. Biomass shall be removed from the target full-scale activated sludge unit and held for no more than 4 hours prior to use in the benchtop bioreactor. If antifoaming agents are used in the full-scale system, they shall also be used in the benchtop bioreactor. The feed flowing into and the effluent exiting the benchtop bioreactor are analyzed to determine the biodegradation rates of the target compounds. The choice of analytical methodology for measuring the compounds of interest at the inlet and outlet to the benchtop bioreactor are left to the discretion of the source, except where validated methods are available.
3.0Definitions [Reserved]
4.0Interferences [Reserved]
5.0Safety
5.1If explosive gases are produced as a byproduct of biodegradation and could realistically pose a hazard, closely monitor headspace concentration of these gases to ensure laboratory safety. Placement of the benchtop bioreactor system inside a laboratory hood is recommended regardless of byproducts produced.
6.0Equipment and Supplies
Note:
Figure 304B-1 illustrates a typical laboratory apparatus used to measure biodegradation rates. While the following description refers to Figure 304B-1, the EPA recognizes that alternative reactor configurations, such as alternative reactor shapes and locations of probes and the feed inlet, will also meet the intent of this method. Ensure that the benchtop bioreactor system is self-contained and isolated from the atmosphere by leak-checking fittings, tubing, etc.
6.1Benchtop Bioreactor. The biological reaction is conducted in a biological oxidation reactor of at least 6-liters capacity. The benchtop bioreactor is sealed and equipped with internal probes for controlling and monitoring dissolved oxygen and internal temperature. The top of the benchtop bioreactor is equipped for aerators, gas flow ports, and instrumentation (while ensuring that no leaks to the atmosphere exist around the fittings).
6.2Aeration gas. Aeration gas is added to the benchtop bioreactor through three diffusers, which are glass tubes that extend to the bottom fifth of the reactor depth. A pure oxygen pressurized cylinder is recommended in order to maintain the specified oxygen concentration. Install a blower (e.g., Diaphragm Type, 15 SCFH capacity) to blow the aeration gas into the benchtop bioreactor diffusers. Measure the aeration gas flow rate with a rotameter (e.g., 0-15 SCFH recommended). The aeration gas will rise through the benchtop bioreactor, dissolving oxygen into the mixture in the process. The aeration gas must provide sufficient agitation to keep the solids in suspension. Provide an exit for the aeration gas from the top flange of the benchtop bioreactor through a water-cooled (e.g., Allihn-type) vertical condenser. Install the condenser through a gas-tight fitting in the benchtop bioreactor closure. Design the system so that at least 10 percent of the gas flows through an alkaline scrubber containing 175 mL of 45 percent by weight solution of potassium hydroxide (KOH) and 5 drops of 0.2 percent alizarin yellow dye. Route the balance of the gas through an adjustable scrubber bypass. Route all of the gas through a 1-L knock-out flask to remove entrained moisture and then to the intake of the blower. The blower recirculates the gas to the benchtop bioreactor.
6.3Wastewater Feed. Supply the wastewater feed to the benchtop bioreactor in a collapsible low-density polyethylene container or collapsible liner in a container (e.g., 20 L) equipped with a spigot cap (collapsible containers or liners of other material may be required due to the permeability of some volatile compounds through polyethylene). Obtain the wastewater feed by sampling the wastewater feed in the target process. A representative sample of wastewater shall be obtained from the piping leading to the aeration tank. This sample may be obtained from existing sampling valves at the discharge of the wastewater feed pump, or collected from a pipe discharging to the aeration tank, or by pumping from a well-mixed equalization tank upstream from the aeration tank. Alternatively, wastewater can be pumped continuously to the laboratory apparatus from a bleed stream taken from the equalization tank of the full-scale treatment system.
6.3.1Refrigeration System. Keep the wastewater feed cool by ice or by refrigeration to 4 °C. If using a bleed stream from the equalization tank, refrigeration is not required if the residence time in the bleed stream is less than five minutes.
6.3.2Wastewater Feed Pump. The wastewater is pumped from the refrigerated container using a variable-speed peristaltic pump drive equipped with a peristaltic pump head. Add the feed solution to the benchtop bioreactor through a fitting on the top flange. Determine the rate of feed addition to provide a retention time in the benchtop bioreactor that is numerically equivalent to the retention time in the target full-scale system. The wastewater shall be fed at a rate sufficient to achieve 90 to 100 percent of the target full-scale system residence time.
6.3.3Treated wastewater feed. The benchtop bioreactor effluent exits at the bottom of the reactor through a tube and proceeds to the clarifier.
6.4Clarifier. The effluent flows to a separate closed clarifier that allows separation of biomass and effluent (e.g., 2-liter pear-shaped glass separatory funnel, modified by removing the stopcock and adding a 25-mm OD glass tube at the bottom). Benchtop bioreactor effluent enters the clarifier through a tube inserted to a depth of 0.08 m (3 in.) through a stopper at the top of the clarifier. System effluent flows from a tube inserted through the stopper at the top of the clarifier to a drain (or sample bottle when sampling). The underflow from the clarifier leaves from the glass tube at the bottom of the clarifier. Flexible tubing connects this fitting to the sludge recycle pump. This pump is coupled to a variable speed pump drive. The discharge from this pump is returned through a tube inserted in a port on the side of the benchtop bioreactor. An additional port is provided near the bottom of the benchtop bioreactor for sampling the reactor contents. The mixed liquor from the benchtop bioreactor flows into the center of the clarifier. The clarified system effluent separates from the biomass and flows through an exit near the top of the clarifier. There shall be no headspace in the clarifier.
6.5Temperature Control Apparatus. Capable of maintaining the system at a temperature equal to the temperature of the full-scale system. The average temperature should be maintained within ±2 °C of the set point.
6.5.1Temperature Monitoring Device. A resistance type temperature probe or a thermocouple connected to a temperature readout with a resolution of 0.1 °C or better.
6.5.2Benchtop Bioreactor Heater. The heater is connected to the temperature control device.
6.6Oxygen Control System. Maintain the dissolved oxygen concentration at the levels present in the full-scale system. Target full-scale activated sludge systems with dissolved oxygen concentration below 2 mg/L are required to maintain the dissolved oxygen concentration in the benchtop bioreactor within 0.5 mg/L of the target dissolved oxygen level. Target full-scale activated sludge systems with dissolved oxygen concentration above 2 mg/L are required to maintain the dissolved oxygen concentration in the benchtop bioreactor within 1.5 mg/L of the target dissolved oxygen concentration; however, for target full-scale activated sludge systems with dissolved oxygen concentrations above 2 mg/L, the dissolved oxygen concentration in the benchtop bioreactor may not drop below 1.5 mg/L. If the benchtop bioreactor is outside the control range, the dissolved oxygen is noted and the reactor operation is adjusted.
6.6.1Dissolved Oxygen Monitor. Dissolved oxygen is monitored with a polarographic probe (gas permeable membrane) connected to a dissolved oxygen meter (e.g., 0 to 15 mg/L, 0 to 50 °C).
6.6.2Benchtop Bioreactor Pressure Monitor. The benchtop bioreactor pressure is monitored through a port in the top flange of the reactor. This is connected to a gauge control with a span of 13-cm water vacuum to 13-cm water pressure or better. A relay is activated when the vacuum exceeds an adjustable setpoint which opens a solenoid valve (normally closed), admitting oxygen to the system. The vacuum setpoint controlling oxygen addition to the system shall be set at approximately 2.5 ±0.5 cm water and maintained at this setting except during brief periods when the dissolved oxygen concentration is adjusted.
6.7Connecting Tubing. All connecting tubing shall be Teflon or equivalent in impermeability. The only exception to this specification is the tubing directly inside the pump head of the wastewater feed pump, which may be Viton, Silicone or another type of flexible tubing.
Note:
Mention of trade names or products does not constitute endorsement by the U.S. Environmental Protection Agency.
7.0.Reagents and Standards
7.1Wastewater. Obtain a representative sample of wastewater at the inlet to the full-scale treatment plant if there is an existing full-scale treatment plant (See Section 6.3). If there is no existing full-scale treatment plant, obtain the wastewater sample as close to the point of determination as possible. Collect the sample by pumping the wastewater into the 20-L collapsible container. The loss of volatiles shall be minimized from the wastewater by collapsing the container before filling, by minimizing the time of filling, and by avoiding a headspace in the container after filling. If the wastewater requires the addition of nutrients to support the biomass growth and maintain biomass characteristics, those nutrients are added and mixed with the container contents after the container is filled.
7.2Biomass. Obtain the biomass or activated sludge used for rate constant determination in the bench-scale process from the existing full-scale process or from a representative biomass culture (e.g., biomass that has been developed for a future full-scale process). This biomass is preferentially obtained from a thickened acclimated mixed liquor sample. Collect the sample either by bailing from the mixed liquor in the aeration tank with a weighted container, or by collecting aeration tank effluent at the effluent overflow weir. Transport the sample to the laboratory within no more than 4 hours of collection. Maintain the biomass concentration in the benchtop bioreactor at the level of the target full-scale system 10 percent throughout the sampling period of the test method.
8.0Sample Collection, Preservation, Storage, and Transport
8.1Benchtop Bioreactor Operation. Charge the mixed liquor to the benchtop bioreactor, minimizing headspace over the liquid surface to minimize entrainment of mixed liquor in the circulating gas. Fasten the benchtop bioreactor headplate to the reactor over the liquid surface. Maintain the temperature of the contents of the benchtop bioreactor system at the temperature of the target full-scale system, ±2 °C, throughout the testing period. Monitor and record the temperature of the reactor contents at least to the nearest 0.1 °C.
8.1.1Wastewater Storage. Collect the wastewater sample in the 20-L collapsible container. Store the container at 4 °C throughout the testing period. Connect the container to the benchtop bioreactor feed pump.
8.1.2Wastewater Flow Rate.
8.1.2.1The hydraulic residence time of the aeration tank is calculated as the ratio of the volume of the tank (L) to the flow rate (L/min). At the beginning of a test, the container shall be connected to the feed pump and solution shall be pumped to the benchtop bioreactor at the required flow rate to achieve the calculated hydraulic residence time of wastewater in the aeration tank.
Where:
Qtest = wastewater flow rate (L/min)
Qfs = average flow rate of full-scale process (L/min)
Vfs = volume of full-scale aeration tank (L)
8.1.2.2The target flow rate in the test apparatus is the same as the flow rate in the target full-scale process multiplied by the ratio of benchtop bioreactor volume (e.g., 6 L) to the volume of the full-scale aeration tank. The hydraulic residence time shall be maintained at 90 to 100 percent of the residence time maintained in the target full-scale unit. A nominal flow rate is set on the pump based on a pump calibration. Changes in the elasticity of the tubing in the pump head and the accumulation of material in the tubing affect this calibration. The nominal pumping rate shall be changed as necessary based on volumetric flow measurements. Discharge the benchtop bioreactor effluent to a wastewater storage, treatment, or disposal facility, except during sampling or flow measurement periods.
8.1.3Sludge Recycle Rate. Set the sludge recycle rate at a rate sufficient to prevent accumulation in the bottom of the clarifier. Set the air circulation rate sufficient to maintain the biomass in suspension.
8.1.4Benchtop Bioreactor Operation and Maintenance. Temperature, dissolved oxygen concentration, flow rate, and air circulation rate shall be measured and recorded three times throughout each day of testing. If other parameters (such as pH) are measured and maintained in the target full-scale unit, these parameters shall, where appropriate, be monitored and maintained to full-scale specifications in the benchtop bioreactor. At the beginning of each sampling period (section 8.2), sample the benchtop bioreactor contents for suspended solids analysis. Take this sample by loosening a clamp on a length of tubing attached to the lower side port. Determine the suspended solids gravimetrically by the Gooch crucible/glass fiber filter method for total suspended solids, in accordance with Standard Methods 3 or equivalent. When necessary, sludge shall be wasted from the lower side port of the benchtop bioreactor, and the volume that is wasted shall be replaced with an equal volume of the benchtop bioreactor effluent. Add thickened activated sludge mixed liquor as necessary to the benchtop bioreactor to increase the suspended solids concentration to the desired level. Pump this mixed liquor to the benchtop bioreactor through the upper side port (Item 24 in Figure 304B-1). Change the membrane on the dissolved oxygen probe before starting the test. Calibrate the oxygen probe immediately before the start of the test and each time the membrane is changed. The scrubber solution shall be replaced each weekday with 175 mL 45 percent W/W KOH solution to which five drops of 0.2 percent alizarin yellow indicator in water have been added. The potassium hydroxide solution in the alkaline scrubber shall be changed if the alizarin yellow dye color changes.
8.1.5Inspection and Correction Procedures. If the feed line tubing becomes clogged, replace with new tubing. If the feed flow rate is not within 5 percent of target flow any time the flow rate is measured, reset pump or check the flow measuring device and measure flow rate again until target flow rate is achieved.
8.2Test Sampling. At least two and one half hydraulic residence times after the system has reached the targeted specifications shall be permitted to elapse before the first sample is taken. Effluent samples of the clarifier discharge (Item 20 in Figure 304B-1) and the influent wastewater feed are collected in 40-mL septum vials to which two drops of 1:10 hydrochloric acid (HCl) in water have been added. Sample the clarifier discharge directly from the drain line. These samples will be composed of the entire flow from the system for a period of several minutes. Feed samples shall be taken from the feed pump suction line after temporarily stopping the benchtop bioreactor feed, removing a connector, and squeezing the collapsible feed container. Store both influent and effluent samples at 4 °C immediately after collection and analyze within 8 hours of collection.
8.2.1Frequency of Sampling. During the test, sample and analyze the wastewater feed and the clarifier effluent at least six times. The sampling intervals shall be separated by at least 8 hours. During any individual sampling interval, sample the wastewater feed simultaneously with or immediately after the effluent sample. Calculate the RSD of the amount removed (i.e., effluent concentration—wastewater feed concentration). The RSD values shall be <15 percent. If an RSD value is >15 percent, continue sampling and analyzing influent and effluent sets of samples until the RSD values are within specifications.
8.2.2Sampling After Exposure of System to Atmosphere. If, after starting sampling procedures, the benchtop bioreactor system is exposed to the atmosphere (due to leaks, maintenance, etc.), allow at least one hydraulic residence time to elapse before resuming sampling.
9.0Quality Control
9.1Dissolved Oxygen. Fluctuation in dissolved oxygen concentration may occur for numerous reasons, including undetected gas leaks, increases and decreases in mixed liquor suspended solids resulting from cell growth and solids loss in the effluent stream, changes in diffuser performance, cycling of effluent flow rate, and overcorrection due to faulty or sluggish dissolved oxygen probe response. Control the dissolved oxygen concentration in the benchtop bioreactor by changing the proportion of oxygen in the circulating aeration gas. Should the dissolved oxygen concentration drift below the designated experimental condition, bleed a small amount of aeration gas from the system on the pressure side (i.e., immediately upstream of one of the diffusers). This will create a vacuum in the system, triggering the pressure sensitive relay to open the solenoid valve and admit oxygen to the system. Should the dissolved oxygen concentration drift above the designated experimental condition, slow or stop the oxygen input to the system until the dissolved oxygen concentration approaches the correct level.
9.2Sludge Wasting.
9.2.1Determine the suspended solids concentration (section 8.1.4) at the beginning of a test, and once per day thereafter during the test. If the test is completed within a two day period, determine the suspended solids concentration after the final sample set is taken. If the suspended solids concentration exceeds the specified concentration, remove a fraction of the sludge from the benchtop bioreactor. The required volume of mixed liquor to remove is determined as follows:
Where:
Vw is the wasted volume (Liters),
Vr is the volume of the benchtop bioreactor (Liters),
Sm is the measured solids (g/L), and
Ss is the specified solids (g/L).
9.2.2Remove the mixed liquor from the benchtop bioreactor by loosening a clamp on the mixed liquor sampling tube and allowing the required volume to drain to a graduated flask. Clamp the tube when the correct volume has been wasted. Replace the volume of the liquid wasted by pouring the same volume of effluent back into the benchtop bioreactor. Dispose of the waste sludge properly.
9.3Sludge Makeup. In the event that the suspended solids concentration is lower than the specifications, add makeup sludge back into the benchtop bioreactor. Determine the amount of sludge added by the following equation:
Where:
Vw is the volume of sludge to add (Liters),
Vr is the volume of the benchtop bioreactor (Liters),
Sw is the solids in the makeup sludge (g/L),
Sm is the measured solids (g/L), and
Ss is the specified solids (g/L).
10.0Calibration and Standardizations
10.1Wastewater Pump Calibration. Determine the wastewater flow rate by collecting the system effluent for a time period of at least one hour, and measuring the volume with a graduated cylinder. Record the collection time period and volume collected. Determine flow rate. Adjust the pump speed to deliver the specified flow rate.
10.2Calibration Standards. Prepare calibration standards from pure certified standards in an aqueous medium. Prepare and analyze three concentrations of calibration standards for each target component (or for a mixture of components) in triplicate daily throughout the analyses of the test samples. At each concentration level, a single calibration shall be within 5 percent of the average of the three calibration results. The low and medium calibration standards shall bracket the expected concentration of the effluent (treated) wastewater. The medium and high standards shall bracket the expected influent concentration.
11.0Analytical Test Procedures
11.1Analysis. If the identity of the compounds of interest in the wastewater is not known, a representative sample of the wastewater shall be analyzed in order to identify all of the compounds of interest present. A gas chromatography/mass spectrometry screening method is recommended.
11.1.1After identifying the compounds of interest in the wastewater, develop and/or use one or more analytical technique capable of measuring each of those compounds (more than one analytical technique may be required, depending on the characteristics of the wastewater). Method 18, found in appendix A of 40 CFR 60, may be used as a guideline in developing the analytical technique. Purge and trap techniques may be used for analysis providing the target components are sufficiently volatile to make this technique appropriate. The limit of quantitation for each compound shall be determined.1 If the effluent concentration of any target compound is below the limit of quantitation determined for that compound, the operation of the Method 304 unit may be altered to attempt to increase the effluent concentration above the limit of quantitation. Modifications to the method shall be approved prior to the test. The request should be addressed to Method 304 contact, Emissions Measurement Center, Mail Drop 19, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711.
12.0Data Analysis and Calculations
12.1Nomenclature. The following symbols are used in the calculations.
Ci = Average inlet feed concentration for a compound of interest, as analyzed (mg/L)
Co = Average outlet (effluent) concentration for a compound of interest, as analyzed (mg/L)
X = Biomass concentration, mixed liquor suspended solids (g/L)
t = Hydraulic residence time in the benchtop bioreactor (hours)
V = Volume of the benchtop bioreactor (L)
Q = Flow rate of wastewater into the benchtop bioreactor, average (L/hour)
12.2Residence Time. The hydraulic residence time of the benchtop bioreactor is equal to the ratio of the volume of the benchtop bioreactor (L) to the flow rate (L/h)
12.3Rate of Biodegradation. Calculate the rate of biodegradation for each component with the following equation:
12.4First-Order Biorate Constant. Calculate the first-order biorate constant (K1) for each component with the following equation:
12.5Relative Standard Deviation (RSD). Determine the standard deviation of both the influent and effluent sample concentrations (S) using the following equation:
12.6Determination of Percent Air Emissions and Percent Biodegraded. Use the results from this test method and follow the applicable procedures in appendix C of 40 CFR part 63, entitled, “Determination of the Fraction Biodegraded (Fbio) in a Biological Treatment Unit” to determine Fbio.
13.0Method Performance [Reserved]
14.0Pollution Prevention [Reserved]
15.0Waste Management [Reserved]
16.0References
1. “Guidelines for data acquisition and data quality evaluation in Environmental Chemistry”, Daniel MacDoughal, Analytical Chemistry, Volume 52, p. 2242, 1980.
2. Test Method 18, 40 CFR 60, Appendix A.
3. Standard Methods for the Examination of Water and Wastewater, 16th Edition, Method 209C, Total Suspended Solids Dried at 103-105 °C, APHA, 1985.
4. Water—7, Hazardous Waste Treatment, Storage, and Disposal Facilities (TSDF)—Air Emission Models, U.S. Environmental Protection Agency, EPA-450/3-87-026, Review Draft, November 1989.
5. Chemdat7, Hazardous Waste Treatment, Storage, and Disposal Facilities (TSDF)—Air Emission Models, U.S. Environmental Protection Agency, EPA-450/3-87-026, Review Draft, November 1989.
17.0Tables, Diagrams, Flowcharts, and Validation Data
Method 305: Measurement of Emission Potential of Individual Volatile Organic Compounds in Waste
Note:
This method does not include all of the specifications (e.g., equipment and supplies) and procedures (e.g., sampling and analytical) essential to its performance. Some material is incorporated by reference from other methods in 40 CFR part 60, appendix A. Therefore, to obtain reliable results, persons using this method should have a thorough knowledge of at least Method 25D.
1.0Scope and Application
1.1Analyte. Volatile Organics. No CAS No. assigned.
1.2Applicability. This procedure is used to determine the emission potential of individual volatile organics (VOs) in waste.
1.3Data Quality Objectives. Adherence to the requirements of this method will enhance the quality of the data obtained from air pollutant sampling methods.
2.0Summary of Method
2.1The heated purge conditions established by Method 25D (40 CFR part 60, appendix A) are used to remove VOs from a 10 gram sample of waste suspended in a 50/50 solution of polyethylene glycol (PEG) and water. The purged VOs are quantified by using the sample collection and analytical techniques (e.g. gas chromatography) appropriate for the VOs present in the waste. The recovery efficiency of the sample collection and analytical technique is determined for each waste matrix. A correction factor is determined for each compound (if acceptable recovery criteria requirements are met of 70 to 130 percent recovery for every target compound), and the measured waste concentration is corrected with the correction factor for each compound. A minimum of three replicate waste samples shall be analyzed.
3.0Definitions [Reserved]
4.0Interferences [Reserved]
5.0Safety
5.1Disclaimer. This method may involve hazardous materials, operations, and equipment. This test method may not address all of the safety problems associated with its use. It is the responsibility of the user of this test method to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to performing this test method.
6.0Equipment and Supplies
6.1Method 25D Purge Apparatus.
6.1.1Purge Chamber. The purge chamber shall accommodate the 10 gram sample of waste suspended in a matrix of 50 mL of PEG and 50 mL of deionized, hydrocarbon-free water. Three fittings are used on the glass chamber top. Two #7 Ace-threads are used for the purge gas inlet and outlet connections. A #50 Ace-thread is used to connect the top of the chamber to the base (see Figure 305-1). The base of the chamber has a side-arm equipped with a #22 Sovirel fitting to allow for easy sample introductions into the chamber. The dimensions of the chamber are shown in Figure 305-1.
6.1.2Flow Distribution Device (FDD). The FDD enhances the gas-to-liquid contact for improved purging efficiency. The FDD is a 6 mm OD (0.2 in) by 30 cm (12 in) long glass tube equipped with four arm bubblers as shown in Figure 305-1. Each arm shall have an opening of 1 mm (0.04 in) in diameter.
6.1.3Coalescing Filter. The coalescing filter serves to discourage aerosol formation of sample gas once it leaves the purge chamber. The glass filter has a fritted disc mounted 10 cm (3.9 in) from the bottom. Two #7 Ace-threads are used for the inlet and outlet connections. The dimensions of the chamber are shown in Figure 305-2.
6.1.4Oven. A forced convection airflow oven capable of maintaining the purge chamber and coalescing filter at 75 ±2 °C (167 ±3.6 °F).
6.1.5Toggle Valve. An on/off valve constructed from brass or stainless steel rated to 100 psig. This valve is placed in line between the purge nitrogen source and the flow controller.
6.1.6Flow Controller. High-quality stainless steel flow controller capable of restricting a flow of nitrogen to 6 ±0.06 L/min (0.2 ±0.002 ft3/min) at 40 psig.
6.1.7Polyethylene Glycol Cleaning System.
6.1.7.1Round-Bottom Flask. One liter, three-neck glass round-bottom flask for cleaning PEG. Standard taper 24/40 joints are mounted on each neck.
6.1.7.2Heating Mantle. Capable of heating contents of the 1-L flask to 120 °C (248 °F).
6.1.7.3Nitrogen Bubbler. Teflon ® or glass tube, 0.25 in OD (6.35 mm).
6.1.7.4Temperature Sensor. Partial immersion glass thermometer.
6.1.7.5Hose Adapter. Glass with 24/40 standard tapered joint.
6.2Volatile Organic Recovery System.
6.2.1Splitter Valve (Optional). Stainless steel cross-pattern valve capable of splitting nominal flow rates from the purge flow of 6 L/min (0.2 ft3/min). The valve shall be maintained at 75 2 °C (167 ±3.6 °F) in the heated zone and shall be placed downstream of the coalescing filter. It is recommended that 0.125 in OD (3.175 mm) tubing be used to direct the split vent flow from the heated zone. The back pressure caused by the 0.125 in OD (3.175 mm) tubing is critical for maintaining proper split valve operation.
Note:
The splitter valve design is optional; it may be used in cases where the concentration of a pollutant would saturate the adsorbents.
6.2.2Injection Port. Stainless steel 1/4 in OD (6.35 mm) compression fitting tee with a 6 mm (0.2 in) septum fixed on the top port. The injection port is the point of entry for the recovery study solution. If using a gaseous standard to determine recovery efficiency, connect the gaseous standard to the injection port of the tee.
6.2.3Knockout Trap (Optional but Recommended). A 25 mL capacity glass reservoir body with a full-stem impinger (to avoid leaks, a modified midget glass impinger with a screw cap and ball/socket clamps on the inlet and outlet is recommended). The empty impinger is placed in an ice water bath between the injection port and the sorbent cartridge. Its purpose is to reduce the water content of the purge gas (saturated at 75 °C (167 °F)) before the sorbent cartridge.
6.2.4Insulated Ice Bath. A 350 mL dewar or other type of insulated bath is used to maintain ice water around the knockout trap.
6.2.5Sorbent Cartridges. Commercially available glass or stainless steel cartridge packed with one or more appropriate sorbents. The amount of adsorbent packed in the cartridge depends on the breakthrough volume of the test compounds but is limited by back pressure caused by the packing (not to exceed 7 psig). More than one sorbent cartridge placed in series may be necessary depending upon the mixture of the measured components.
6.2.6Volumetric Glassware. Type A glass 10 mL volumetric flasks for measuring a final volume from the water catch in the knockout trap.
6.2.7Thermal Desorption Unit. A clam-shell type oven, used for the desorption of direct thermal desorption sorbent tubes. The oven shall be capable of increasing the temperature of the desorption tubes rapidly to recommended desorption temperature.
6.2.8Ultrasonic Bath. Small bath used to agitate sorbent material and desorption solvent. Ice water shall be used in the bath because of heat transfer caused by operation of the bath.
6.2.9Desorption Vials. Four-dram (15 mL) capacity borosilicate glass vials with Teflon-lined caps.
6.3Analytical System. A gas chromatograph (GC) is commonly used to separate and quantify compounds from the sample collection and recovery procedure. Method 18 (40 CFR part 60, appendix A) may be used as a guideline for determining the appropriate GC column and GC detector based on the test compounds to be determined. Other types of analytical instrumentation may be used (HPLC) in lieu of GC systems as long as the recovery efficiency criteria of this method are met.
6.3.1Gas Chromatograph (GC). The GC shall be equipped with a constant-temperature liquid injection port or a heated sampling loop/valve system, as appropriate. The GC oven shall be temperature-programmable over the useful range of the GC column. The choice of detectors is based on the test compounds to be determined.
6.3.2GC Column. Select the appropriate GC column based on (1) literature review or previous experience, (2) polarity of the analytes, (3) capacity of the column, or (4) resolving power (e.g., length, diameter, film thickness) required.
6.3.3Data System. A programmable electronic integrator for recording, analyzing, and storing the signal generated by the detector.
7.0Reagents and Standards
7.1Method 25D Purge Apparatus.
7.1.1Polyethylene Glycol (PEG). Ninety-eight percent pure organic polymer with an average molecular weight of 400 g/mol. Volatile organics are removed from the PEG prior to use by heating to 120 ±5 °C (248 ±9 °F) and purging with pure nitrogen at 1 L/min (0.04 ft3/min) for 2 hours. After purging and heating, the PEG is maintained at room temperature under a nitrogen purge maintained at 1 L/min (0.04 ft3/min) until used. A typical apparatus used to clean the PEG is shown in Figure 305-3.
7.1.2Water. Organic-free deionized water is required.
7.1.3Nitrogen. High-purity nitrogen (less than 0.5 ppm total hydrocarbons) is used to remove test compounds from the purge matrix. The source of nitrogen shall be regulated continuously to 40 psig before the on/off toggle valve.
7.2Volatile Organic Recovery System.
7.2.1Water. Organic-free deionized water is required.
7.2.2Desorption Solvent (when used). Appropriate high-purity (99.99 percent) solvent for desorption shall be used. Analysis shall be performed (utilizing the same analytical technique as that used in the analysis of the waste samples) on each lot to determine purity.
7.3Analytical System. The gases required for GC operation shall be of the highest obtainable purity (hydrocarbon free). Consult the operating manual for recommended settings.
8.0Sample Collection, Preservation, Storage, and Transport
8.1Assemble the glassware and associated fittings (see Figures 305-3 and 305-4, as appropriate) and leak-check the system (approximately 7 psig is the target pressure). After an initial leak check, mark the pressure gauge and use the initial checkpoint to monitor for leaks throughout subsequent analyses. If the pressure in the system drops below the target pressure at any time during analysis, that analysis shall be considered invalid.
8.2Recovery Efficiency Determination. Determine the individual recovery efficiency (RE) for each of the target compounds in duplicate before the waste samples are analyzed. To determine the RE, generate a water blank (Section 11.1) and use the injection port to introduce a known volume of spike solution (or certified gaseous standard) containing all of the target compounds at the levels expected in the waste sample. Introduce the spike solution immediately after the nitrogen purge has been started (Section 8.3.2). Follow the procedures outlined in Section 8.3.3. Analyze the recovery efficiency samples using the techniques described in Section 11.2. Determine the recovery efficiency (Equation 305-1, Section 12.2) by comparing the amount of compound recovered to the theoretical amount spiked. Determine the RE twice for each compound; the relative standard deviation, (RSD) shall be ≤10 percent for each compound. If the RSD for any compound is not ≤ 10 percent, modify the sampling/analytical procedure and complete an RE study in duplicate, or continue determining RE until the RSD meets the acceptable criteria. The average RE shall be 0.70 ≤ RE ≤ 1.30 for each compound. If the average RE does not meet these criteria, an alternative sample collection and/or analysis technique shall be developed and the recovery efficiency determination shall be repeated for that compound until the criteria are met for every target compound. Example modifications of the sampling/analytical system include changing the adsorbent material, changing the desorption solvent, utilizing direct thermal desorption of test compounds from the sorbent tubes, utilizing another analytical technique.
8.3Sample Collection and Recovery.
8.3.1The sample collection procedure in Method 25D shall be used to collect (into a preweighed vial) 10 g of waste into PEG, cool, and ship to the laboratory. Remove the sample container from the cooler and wipe the exterior to remove any ice or water. Weigh the container and sample to the nearest 0.01 g and record the weight. Pour the sample from the container into the purge flask. Rinse the sample container three times with approximately 6 mL of PEG (or the volume needed to total 50 mL of PEG in the purge flask), transferring the rinses to the purge flask. Add 50 mL of organic-free deionized water to the purge flask. Cap the purge flask tightly in between each rinse and after adding all the components into the flask.
8.3.2Allow the oven to equilibrate to 75 ±2 °C (167 ±3.6 °F). Begin the sample recovery process by turning the toggle valve on, thus allowing a 6 L/min flow of pure nitrogen through the purge chamber.
8.3.3Stop the purge after 30 min. Immediately remove the sorbent tube(s) from the apparatus and cap both ends. Remove the knockout trap and transfer the water catch to a 10 mL volumetric flask. Rinse the trap with organic-free deionized water and transfer the rinse to the volumetric flask. Dilute to the 10 mL mark with water. Transfer the water sample to a sample vial and store at 4 °C (39.2 °F) with zero headspace. The analysis of the contents of the water knockout trap is optional for this method. If the target compounds are water soluble, analysis of the water is recommended; meeting the recovery efficiency criteria in these cases would be difficult without adding the amount captured in the knockout trap.
9.0Quality Control
9.1Miscellaneous Quality Control Measures.
Section Quality control measure Effect
8.1 Sampling equipment leak-check Ensures accurate measurement of sample volume.
8.2 Recovery efficiency (RE) determination for each measured compound. Ensures accurate sample collection and analysis.
8.3 Calibration of analytical instrument with at least 3 calibration standards. Ensures linear measurement of compounds over the instrument span.
10.0Calibration and Standardization
10.1The analytical instrument shall be calibrated with a minimum of three levels of standards for each compound whose concentrations bracket the concentration of test compounds from the sorbent tubes. Liquid calibration standards shall be used for calibration in the analysis of the solvent extracts. The liquid calibration standards shall be prepared in the desorption solvent matrix. The calibration standards may be prepared and injected individually or as a mixture. If thermal desorption and focusing (onto another sorbent or cryogen focusing) are used, a certified gaseous mixture or a series of gaseous standards shall be used for calibration of the instrument. The gaseous standards shall be focused and analyzed in the same manner as the samples.
10.2The analytical system shall be certified free from contaminants before a calibration is performed (see Section 11.1). The calibration standards are used to determine the linearity of the analytical system. Perform an initial calibration and linearity check by analyzing the three calibration standards for each target compound in triplicate starting with the lowest level and continuing to the highest level. If the triplicate analyses do not agree within 5 percent of their average, additional analyses will be needed until the 5 percent criteria is met. Calculate the response factor (Equation 305-3, Section 12.4) from the average area counts of the injections for each concentration level. Average the response factors of the standards for each compound. The linearity of the detector is acceptable if the response factor of each compound at a particular concentration is within 10 percent of the overall mean response factor for that compound. Analyze daily a mid-level calibration standard in duplicate and calculate a new response factor. Compare the daily response factor average to the average response factor calculated for the mid-level calibration during the initial linearity check; repeat the three-level calibration procedure if the daily average response factor differs from the initial linearity check mid-level response factor by more than 10 percent. Otherwise, proceed with the sample analysis.
11.0Analytical Procedure
11.1Water Blank Analysis. A water blank shall be analyzed daily to determine the cleanliness of the purge and recovery system. A water blank is generated by adding 60 mL of organic-free deionized water to 50 mL of PEG in the purge chamber. Treat the blank as described in Sections 8.3.2 and 8.3.3. The purpose of the water blank is to insure that no contaminants exist in the sampling and analytical apparatus which would interfere with the quantitation of the target compounds. If contaminants are present, locate the source of contamination, remove it, and repeat the water blank analysis.
11.2Sample Analysis. Sample analysis in the context of this method refers to techniques to remove the target compounds from the sorbent tubes, separate them using a chromatography technique, and quantify them with an appropriate detector. Two types of sample extraction techniques typically used for sorbents include solvent desorption or direct thermal desorption of test compounds to a secondary focusing unit (either sorbent or cryogen based). The test compounds are then typically transferred to a GC system for analysis. Other analytical systems may be used (e.g., HPLC) in lieu of GC systems as long as the recovery efficiency criteria of this method are met.
11.2.1Recover the test compounds from the sorbent tubes that require solvent desorption by transferring the adsorbent material to a sample vial containing the desorption solvent. The desorption solvent shall be the same as the solvent used to prepare calibration standards. The volume of solvent depends on the amount of adsorbed material to be desorbed (1.0 mL per 100 mg of adsorbent material) and also on the amount of test compounds present. Final volume adjustment and or dilution can be made so that the concentration of test compounds in the desorption solvent is bracketed by the concentration of the calibration solutions. Ultrasonicate the desorption solvent for 15 min in an ice bath. Allow the sample to sit for a period of time so that the adsorbent material can settle to the bottom of the vial. Transfer the solvent with a pasteur pipet (minimizing the amount of adsorbent material taken) to another vial and store at 4 °C (39.2 °F).
11.2.2Analyze the desorption solvent or direct thermal desorption tubes from each sample using the same analytical parameters used for the calibration standard. Calculate the total weight detected for each compound (Equation 305-4, Section 12.5). The slope (area/amount) and y-intercept are calculated from the line bracketed between the two closest calibration points. Correct the concentration of each waste sample with the appropriate recovery efficiency factor and the split flow ratio (if used). The final concentration of each individual test compound is calculated by dividing the corrected measured weight for that compound by the weight of the original sample determined in Section 8.3.1 (Equation 305-5, Section 12.6).
11.2.3Repeat the analysis for the three samples collected in Section 8.3. Report the corrected concentration of each of the waste samples, average waste concentration, and relative standard deviation (Equation 305-6, Section 12.7).
12.0Data Analysis and Calculations.
12.1Nomenclature.
AS = Mean area counts of test compound in standard.
AU = Mean area counts of test compound in sample desorption solvent.
b = Y-intercept of the line formed between the two closest calibration standards that bracket the concentration of the sample.
CT = Amount of test compound (µg) in calibration standard.
CF = Correction for adjusting final amount of sample detected for losses during individual sample runs.
FP = Nitrogen flow through the purge chamber (6 L/min).
FS = Nitrogen split flow directed to the sample recovery system (use 6 L/min if split flow design was not used).
PPM = Final concentration of test compound in waste sample [µg/g (which is equivalent to parts per million by weight (ppmw))].
RE = Recovery efficiency for adjusting final amount of sample detected for losses due to inefficient trapping and desorption techniques.
R.F. = Response factor for test compound, calculated from a calibration standard.
S = Slope of the line (area counts/CT) formed between two closest calibration points that bracket the concentration of the sample.
WC = Weight of test compound expected to be recovered in spike solution based on theoretical amount (µg).
WE = Weight of vial and PEG (g).
WF = Weight of vial, PEG and waste sample (g).
WS = Weight of original waste sample (g).
WT = Corrected weight of test compound measured (µg) in sample.
WX = Weight of test compound measured during analysis of recovery efficiency spike samples (µg).
12.2Recovery efficiency for determining trapping/desorption efficiency of individual test compounds in the spike solution, decimal value.
12.3Weight of waste sample (g).
12.4Response factor for individual test compounds.
12.5Corrected weight of a test compound in the sample, in µg.
12.6Final concentration of a test compound in the sample in ppmw.
12.7Relative standard deviation (RSD) calculation.
13.0Method Performance [Reserved]
14.0Pollution Prevention [Reserved]
15.0Waste Management [Reserved]
16.0References [Reserved]
17.0Tables, Diagrams, Flowcharts, and Validation Data
Method 306—Determination of Chromium Emissions From Decorative and Hard Chromium Electroplating and Chromium Anodizing Operations—Isokinetic Method
Note:
This method does not include all of the specifications (e.g., equipment and supplies) and procedures (e.g., sampling and analytical) essential to its performance. Some material is incorporated by reference from other methods in 40 CFR part 60, appendix A. Therefore, to obtain reliable results, persons using this method should have a thorough knowledge of at least Method 5.
1.0Scope and Application
1.1Analytes.
Analyte CAS No. Sensitivity
Chromium 7440-47-3 See Sec. 13.2.
1.2Applicability. This method applies to the determination of chromium (Cr) in emissions from decorative and hard chrome electroplating facilities, chromium anodizing operations, and continuous chromium plating operations at iron and steel facilities.
1.3Data Quality Objectives. [Reserved]
2.0Summary of Method
2.1Sampling. An emission sample is extracted isokinetically from the source using an unheated Method 5 sampling train (40 CFR part 60, appendix A), with a glass nozzle and probe liner, but with the filter omitted. The sample time shall be at least two hours. The Cr emissions are collected in an alkaline solution containing 0.1 N sodium hydroxide (NaOH) or 0.1 N sodium bicarbonate (NaHCO3). The collected samples are recovered using an alkaline solution and are then transported to the laboratory for analysis.
2.2Analysis.
2.2.1Total chromium samples with high chromium concentrations (≥35 µg/L) may be analyzed using inductively coupled plasma emission spectrometry (ICP) at 267.72 nm.
Note:
The ICP analysis is applicable for this method only when the solution analyzed has a Cr concentration greater than or equal to 35 µg/L or five times the method detection limit as determined according to Appendix B in 40 CFR part 136.
2.2.2Alternatively, when lower total chromium concentrations (<35 µg/L) are encountered, a portion of the alkaline sample solution may be digested with nitric acid and analyzed by graphite furnace atomic absorption spectroscopy (GFAAS) at 357.9 nm.
2.2.3If it is desirable to determine hexavalent chromium (Cr 6) emissions, the samples may be analyzed using an ion chromatograph equipped with a post-column reactor (IC/PCR) and a visible wavelength detector. To increase sensitivity for trace levels of Cr 6, a preconcentration system may be used in conjunction with the IC/PCR.
3.0Definitions
3.1Total Chromium—measured chromium content that includes both major chromium oxidation states (Cr 3, Cr 3).
3.2May—Implies an optional operation.
3.3Digestion—The analytical operation involving the complete (or nearly complete) dissolution of the sample in order to ensure the complete solubilization of the element (analyte) to be measured.
3.4Interferences—Physical, chemical, or spectral phenomena that may produce a high or low bias in the analytical result.
3.5Analytical System—All components of the analytical process including the sample digestion and measurement apparatus.
3.6Sample Recovery—The quantitative transfer of sample from the collection apparatus to the sample preparation (digestion, etc.) apparatus. This term should not be confused with analytical recovery.
3.7Matrix Modifier—A chemical modification to the sample during GFAAS determinations to ensure that the analyte is not lost during the measurement process (prior to the atomization stage)
3.8Calibration Reference Standards—Quality control standards used to check the accuracy of the instrument calibration curve prior to sample analysis.
3.9Continuing Check Standard—Quality control standards used to verify that unacceptable drift in the measurement system has not occurred.
3.10Calibration Blank—A blank used to verify that there has been no unacceptable shift in the baseline either immediately following calibration or during the course of the analytical measurement.
3.11Interference Check—An analytical/measurement operation that ascertains whether a measurable interference in the sample exists.
3.12Interelement Correction Factors—Factors used to correct for interfering elements that produce a false signal (high bias).
3.13Duplicate Sample Analysis—Either the repeat measurement of a single solution or the measurement of duplicate preparations of the same sample. It is important to be aware of which approach is required for a particular type of measurement. For example, no digestion is required for the ICP determination and the duplicate instrument measurement is therefore adequate whereas duplicate digestion/instrument measurements are required for GFAAS.
3.14Matrix Spiking—Analytical spikes that have been added to the actual sample matrix either before (Section 9.2.5.2) or after (Section 9.1.6). Spikes added to the sample prior to a preparation technique (e.g., digestion) allow for the assessment of an overall method accuracy while those added after only provide for the measurement accuracy determination.
4.0Interferences
4.1ICP Interferences.
4.1.1ICP Spectral Interferences. Spectral interferences are caused by: overlap of a spectral line from another element; unresolved overlap of molecular band spectra; background contribution from continuous or recombination phenomena; and, stray light from the line emission of high-concentrated elements. Spectral overlap may be compensated for by correcting the raw data with a computer and measuring the interfering element. At the 267.72 nm Cr analytical wavelength, iron, manganese, and uranium are potential interfering elements. Background and stray light interferences can usually be compensated for by a background correction adjacent to the analytical line. Unresolved overlap requires the selection of an alternative chromium wavelength. Consult the instrument manufacturer's operation manual for interference correction procedures.
4.1.2ICP Physical Interferences. High levels of dissolved solids in the samples may cause significant inaccuracies due to salt buildup at the nebulizer and torch tips. This problem can be controlled by diluting the sample or by extending the rinse times between sample analyses. Standards shall be prepared in the same solution matrix as the samples (i.e., 0.1 N NaOH or 0.1 N NaHCO3).
4.1.3ICP Chemical Interferences. These include molecular compound formation, ionization effects and solute vaporization effects, and are usually not significant in the ICP procedure, especially if the standards and samples are matrix matched.
4.2GFAAS Interferences.
4.2.1GFAAS Chemical Interferences. Low concentrations of calcium and/or phosphate may cause interferences; at concentrations above 200 µg/L, calcium's effect is constant and eliminates the effect of phosphate. Calcium nitrate is therefore added to the concentrated analyte to ensure a known constant effect. Other matrix modifiers recommended by the instrument manufacturer may also be considered.
4.2.2GFAAS Cyanide Band Interferences. Nitrogen should not be used as the purge gas due to cyanide band interference.
4.2.3GFAAS Spectral Interferences. Background correction may be required because of possible significant levels of nonspecific absorption and scattering at the 357.9 nm analytical wavelength.
4.2.4GFAAS Background Interferences. Zeeman or Smith-Hieftje background correction is recommended for interferences resulting from high levels of dissolved solids in the alkaline impinger solutions.
4.3IC/PCR Interferences.
4.3.1IC/PCR Chemical Interferences. Components in the sample matrix may cause Cr 6 to convert to trivalent chromium (Cr 3) or cause Cr 3 to convert to Cr 6. The chromatographic separation of Cr 6 using ion chromatography reduces the potential for other metals to interfere with the post column reaction. For the IC/PCR analysis, only compounds that coelute with Cr 6 and affect the diphenylcarbazide reaction will cause interference.
4.3.2IC/PCR Background Interferences. Periodic analyses of reagent water blanks are used to demonstrate that the analytical system is essentially free of contamination. Sample cross-contamination can occur when high-level and low-level samples or standards are analyzed alternately and can be eliminated by thorough purging of the sample loop. Purging of the sample can easily be achieved by increasing the injection volume to ten times the size of the sample loop.
5.0Safety
5.1Disclaimer. This method may involve hazardous materials, operations, and equipment. This test method may not address all of the safety problems associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to performing this test method.
5.2Hexavalent chromium compounds have been listed as carcinogens although chromium (III) compounds show little or no toxicity. Chromium can be a skin and respiratory irritant.
6.0Equipment and Supplies
6.1Sampling Train.
6.1.1A schematic of the sampling train used in this method is shown in Figure 306-1. The train is the same as shown in Method 5, Section 6.0 (40 CFR part 60, appendix A) except that the probe liner is unheated, the particulate filter is omitted, and quartz or borosilicate glass must be used for the probe nozzle and liner in place of stainless steel.
6.1.2Probe fittings of plastic such as Teflon, polypropylene, etc. are recommended over metal fittings to prevent contamination. If desired, a single combined probe nozzle and liner may be used, but such a single glass assembly is not a requirement of this methodology.
6.1.3Use 0.1 N NaOH or 0.1 N NaHCO3 in the impingers in place of water.
6.1.4Operating and maintenance procedures for the sampling train are described in APTD-0576 of Method 5. Users should read the APTD-0576 document and adopt the outlined procedures.
6.1.5Similar collection systems which have been approved by the Administrator may be used.
6.2Sample Recovery. Same as Method 5, [40 CFR part 60, appendix A], with the following exceptions:
6.2.1Probe-Liner and Probe-Nozzle Brushes. Brushes are not necessary for sample recovery. If a probe brush is used, it must be non-metallic.
6.2.2Sample Recovery Solution. Use 0.1 N NaOH or 0.1 N NaHCO3, whichever is used as the impinger absorbing solution, in place of acetone to recover the sample.
6.2.3Sample Storage Containers. Polyethylene, with leak-free screw cap, 250 mL, 500 mL or 1,000 mL.
6.3Analysis.
6.3.1General. For analysis, the following equipment is needed.
6.3.1.1Phillips Beakers. (Phillips beakers are preferred, but regular beakers may also be used.)
6.3.1.2Hot Plate.
6.3.1.3Volumetric Flasks. Class A, various sizes as appropriate.
6.3.1.4Assorted Pipettes.
6.3.2Analysis by ICP.
6.3.2.1ICP Spectrometer. Computer-controlled emission spectrometer with background correction and radio frequency generator.
6.3.2.2Argon Gas Supply. Welding grade or better.
6.3.3Analysis by GFAAS.
6.3.3.1Chromium Hollow Cathode Lamp or Electrodeless Discharge Lamp.
6.3.3.2Graphite Furnace Atomic Absorption Spectrophotometer.
6.3.3.3Furnace Autosampler.
6.3.4Analysis by IC/PCR.
6.3.4.1IC/PCR System. High performance liquid chromatograph pump, sample injection valve, post-column reagent delivery and mixing system, and a visible detector, capable of operating at 520 nm-540 nm, all with a non-metallic (or inert) flow path. An electronic peak area mode is recommended, but other recording devices and integration techniques are acceptable provided the repeatability criteria and the linearity criteria for the calibration curve described in Section 10.4 can be satisfied. A sample loading system is required if preconcentration is employed.
6.3.4.2Analytical Column. A high performance ion chromatograph (HPIC) non-metallic column with anion separation characteristics and a high loading capacity designed for separation of metal chelating compounds to prevent metal interference. Resolution described in Section 11.6 must be obtained. A non-metallic guard column with the same ion-exchange material is recommended.
6.3.4.3Preconcentration Column (for older instruments). An HPIC non-metallic column with acceptable anion retention characteristics and sample loading rates must be used as described in Section 11.6.
6.3.4.4Filtration Apparatus for IC/PCR.
6.3.4.4.1Teflon, or equivalent, filter holder to accommodate 0.45-µm acetate, or equivalent, filter, if needed to remove insoluble particulate matter.
6.3.4.4.20.45-µm Filter Cartridge. For the removal of insoluble material. To be used just prior to sample injection/analysis.
7.0Reagents and Standards
Note:
Unless otherwise indicated, all reagents should conform to the specifications established by the Committee on Analytical Reagents of the American Chemical Society (ACS reagent grade). Where such specifications are not available, use the best available grade. Reagents should be checked by the appropriate analysis prior to field use to assure that contamination is below the analytical detection limit for the ICP or GFAAS total chromium analysis; and that contamination is below the analytical detection limit for Cr 6 using IC/PCR for direct injection or, if selected, preconcentration.
7.1Sampling.
7.1.1Water. Reagent water that conforms to ASTM Specification D1193-77 or 91 Type II (incorporated by reference see § 63.14). All references to water in the method refer to reagent water unless otherwise specified. It is recommended that water blanks be checked prior to preparing the sampling reagents to ensure that the Cr content is less than three (3) times the anticipated detection limit of the analytical method.
7.1.2Sodium Hydroxide (NaOH) Absorbing Solution, 0.1 N. Dissolve 4.0 g of sodium hydroxide in 1 liter of water to obtain a pH of approximately 8.5.
7.1.3Sodium Bicarbonate (NaHCO3) Absorbing Solution, 0.1 N. Dissolve approximately 8.5 g of sodium bicarbonate in 1 liter of water to obtain a pH of approximately 8.3.
7.1.4Chromium Contamination.
7.1.4.1The absorbing solution shall not exceed the QC criteria noted in Section 7.1.1 (≤ 3 times the instrument detection limit).
7.1.4.2When the Cr 6 content in the field samples exceeds the blank concentration by at least a factor of ten (10), Cr 6 blank concentrations ≥ 10 times the detection limit will be allowed.
Note:
At sources with high concentrations of acids and/or SO2, the concentration of NaOH or NaHCO3 should be ≥ 0.5 N to insure that the pH of the solution remains at or above 8.5 for NaOH and 8.0 for NaHCO3 during and after sampling.
7.1.5Silica Gel. Same as in Method 5.
7.2Sample Recovery.
7.2.10.1 N NaOH or 0.1 N NaHCO3. Use the same solution for the sample recovery that is used for the impinger absorbing solution.
7.2.2pH Indicator Strip, for IC/PCR. pH indicator capable of determining the pH of solutions between the pH range of 7 and 12, at 0.5 pH increments.
7.3Sample Preparation and Analysis.
7.3.1Nitric Acid (HNO3), Concentrated, for GFAAS. Trace metals grade or better HNO3 must be used for reagent preparation. The ACS reagent grade HNO3 is acceptable for cleaning glassware.
7.3.2HNO3, 1.0% (v/v), for GFAAS. Prepare, by slowly stirring, 10 mL of concentrated HNO3) into 800 mL of reagent water. Dilute to 1,000 mL with reagent water. The solution shall contain less than 0.001 mg Cr/L.
7.3.3Calcium Nitrate Ca(NO3)2 Solution (10 µg Ca/mL) for GFAAS analysis. Prepare the solution by weighing 40.9 mg of Ca(NO3)2 into a 1 liter volumetric flask. Dilute with reagent water to 1 liter.
7.3.4Matrix Modifier, for GFAAS. See instrument manufacturer's manual for suggested matrix modifier.
7.3.5Chromatographic Eluent, for IC/PCR. The eluent used in the analytical system is ammonium sulfate based.
7.3.5.1Prepare by adding 6.5 mL of 29 percent ammonium hydroxide (NH4OH) and 33 g of ammonium sulfate ((NH4)2SO4) to 500 mL of reagent water. Dilute to 1 liter with reagent water and mix well.
7.3.5.2Other combinations of eluents and/or columns may be employed provided peak resolution, repeatability, linearity, and analytical sensitivity as described in Sections 9.3 and 11.6 are acceptable.
7.3.6Post-Column Reagent, for IC/PCR. An effective post-column reagent for use with the chromatographic eluent described in Section 7.3.5 is a diphenylcarbazide (DPC)-based system. Dissolve 0.5 g of 1,5-diphenylcarbazide in 100 mL of ACS grade methanol. Add 500 mL of reagent water containing 50 mL of 96 percent spectrophotometric grade sulfuric acid. Dilute to 1 liter with reagent water.
7.3.7Chromium Standard Stock Solution (1000 mg/L). Procure a certified aqueous standard or dissolve 2.829 g of potassium dichromate (K2Cr2O7), in reagent water and dilute to 1 liter.
7.3.8Calibration Standards for ICP or IC/PCR. Prepare calibration standards for ICP or IC/PCR by diluting the Cr standard stock solution (Section 7.3.7) with 0.1 N NaOH or 0.1 N NaHCO3, whichever is used as the impinger absorbing solution, to achieve a matrix similar to the actual field samples. Suggested levels are 0, 50, 100, and 200 µg Cr/L for ICP, and 0, 1, 5, and 10 µg Cr 6/L for IC/PCR.
7.3.9Calibration Standards for GFAAS. Chromium solutions for GFAAS calibration shall contain 1.0 percent (v/v) HNO3. The zero standard shall be 1.0 percent (v/v) HNO3. Calibration standards should be prepared daily by diluting the Cr standard stock solution (Section 7.3.7) with 1.0 percent HNO3. Use at least four standards to make the calibration curve. Suggested levels are 0, 10, 50, and 100 µg Cr/L.
7.4Glassware Cleaning Reagents.
7.4.1HNO3, Concentrated. ACS reagent grade or equivalent.
7.4.2Water. Reagent water that conforms to ASTM Specification D1193-77 or 91 Type II.
7.4.3HNO3, 10 percent (v/v). Add by stirring 500 mL of concentrated HNO3 into a flask containing approximately 4,000 mL of reagent water. Dilute to 5,000 mL with reagent water. Mix well. The reagent shall contain less than 2 µg Cr/L.
8.0Sample Collection, Preservation, Holding Times, Storage, and Transport
Note:
Prior to sample collection, consideration should be given to the type of analysis (Cr 6 or total Cr) that will be performed. Which analysis option(s) will be performed will determine which sample recovery and storage procedures will be required to process the sample (See Figures 306-3 and 306-4).
8.1Sample Collection. Same as Method 5 (40 CFR part 60, appendix A), with the following exceptions.
8.1.1Omit the particulate filter and filter holder from the sampling train. Use a glass nozzle and probe liner instead of stainless steel. Do not heat the probe. Place 100 mL of 0.1 N NaOH or 0.1 N NaHCO3 in each of the first two impingers, and record the data for each run on a data sheet such as shown in Figure 306-2.
8.1.2Clean all glassware prior to sampling in hot soapy water designed for laboratory cleaning of glassware. Next, rinse the glassware three times with tap water, followed by three additional rinses with reagent water. Then soak the glassware in 10% (v/v) HNO3 solution for a minimum of 4 hours, rinse three times with reagent water, and allow to air dry. Cover all glassware openings where contamination can occur with Parafilm, or equivalent, until the sampling train is assembled for sampling.
8.1.3Train Operation. Follow the basic procedures outlined in Method 5 in conjunction with the following instructions. Train sampling rate shall not exceed 0.030 m3/min (1.0 cfm) during a run.
8.2Sample Recovery. Follow the basic procedures of Method 5, with the exceptions noted.
8.2.1A particulate filter is not recovered from this train.
8.2.2Tester shall select either the total Cr or Cr 6 sample recovery option.
8.2.3Samples to be analyzed for both total Cr and Cr 6, shall be recovered using the Cr 6 sample option (Section 8.2.6).
8.2.4A field reagent blank shall be collected for either of the Cr or the Cr 6 analysis. If both analyses (Cr and Cr 6) are to be conducted on the samples, collect separate reagent blanks for each analysis.
Note:
Since particulate matter is not usually present at chromium electroplating and/or chromium anodizing operations, it is not necessary to filter the Cr 6 samples unless there is observed sediment in the collected solutions. If it is necessary to filter the Cr 6 solutions, please refer to Method 0061, Determination of Hexavalent Chromium Emissions From Stationary Sources, Section 7.4, Sample Preparation in SW-846 (see Reference 1).
8.2.5Total Cr Sample Option.
8.2.5.1Container No. 1. Measure the volume of the liquid in the first, second, and third impingers and quantitatively transfer into a labeled sample container.
8.2.5.2Use approximately 200 to 300 mL of the 0.1 N NaOH or 0.1 N NaHCO3 absorbing solution to rinse the probe nozzle, probe liner, three impingers, and connecting glassware; add this rinse to Container No. 1.
8.2.6Cr 6 Sample Option.
8.2.6.1Container No. 1. Measure and record the pH of the absorbing solution contained in the first impinger at the end of the sampling run using a pH indicator strip. The pH of the solution must be ≥8.5 for NaOH and ≥8.0 for NaHCO3. If it is not, discard the collected sample, increase the normality of the NaOH or NaHCO3 impinger absorbing solution to 0.5 N or to a solution normality approved by the Administrator and collect another air emission sample.
8.2.6.2After determining the pH of the first impinger solution, combine and measure the volume of the liquid in the first, second, and third impingers and quantitatively transfer into the labeled sample container. Use approximately 200 to 300 mL of the 0.1 N NaOH or 0.1 N NaHCO3 absorbing solution to rinse the probe nozzle, probe liner, three impingers, and connecting glassware; add this rinse to Container No. 1.
8.2.7Field Reagent Blank.
8.2.7.1Container No. 2.
8.2.7.2Place approximately 500 mL of the 0.1 N NaOH or 0.1 N NaHCO3 absorbing solution into a labeled sample container.
8.3Sample Preservation, Storage, and Transport.
8.3.1Total Cr Sample Option. Samples to be analyzed for total Cr need not be refrigerated.
8.3.2Cr 6 Sample Option. Samples to be analyzed for Cr 6 must be shipped and stored at 4 °C. Allow Cr 6 samples to return to ambient temperature prior to analysis.
8.4Sample Holding Times.
8.4.1Total Cr Sample Option. Samples to be analyzed for total Cr shall be analyzed within 60 days of collection.
8.4.2Cr 6 Sample Option. Samples to be analyzed for Cr 6 shall be analyzed within 14 days of collection.
9.0Quality Control
9.1ICP Quality Control.
9.1.1ICP Calibration Reference Standards. Prepare a calibration reference standard using the same alkaline matrix as the calibration standards; it should be at least 10 times the instrumental detection limit.
9.1.1.1This reference standard must be prepared from a different Cr stock solution source than that used for preparation of the calibration curve standards.
9.1.1.2Prior to sample analysis, analyze at least one reference standard.
9.1.1.3The calibration reference standard must be measured within 10 percent of it's true value for the curve to be considered valid.
9.1.1.4The curve must be validated before sample analyses are performed.
9.1.2ICP Continuing Check Standard.
9.1.2.1Perform analysis of the check standard with the field samples as described in Section 11.2 (at least after every 10 samples, and at the end of the analytical run).
9.1.2.2The check standard can either be the mid-range calibration standard or the reference standard. The results of the check standard shall agree within 10 percent of the expected value; if not, terminate the analyses, correct the problem, recalibrate the instrument, and rerun all samples analyzed subsequent to the last acceptable check standard analysis.
9.1.3ICP Calibration Blank.
9.1.3.1Perform analysis of the calibration blank with the field samples as described in Section 11.2 (at least after every 10 samples, and at the end of the analytical run).
9.1.3.2The results of the calibration blank shall agree within three standard deviations of the mean blank value. If not, analyze the calibration blank two more times and average the results. If the average is not within three standard deviations of the background mean, terminate the analyses, correct the problem, recalibrate, and reanalyze all samples analyzed subsequent to the last acceptable calibration blank analysis.
9.1.4ICP Interference Check. Prepare an interference check solution that contains known concentrations of interfering elements that will provide an adequate test of the correction factors in the event of potential spectral interferences.
9.1.4.1Two potential interferences, iron and manganese, may be prepared as 1000 µg/mL and 200 µg/mL solutions, respectively. The solutions should be prepared in dilute HNO3 (1-5 percent). Particular care must be used to ensure that the solutions and/or salts used to prepare the solutions are of ICP grade purity (i.e., that no measurable Cr contamination exists in the salts/solutions). Commercially prepared interfering element check standards are available.
9.1.4.2Verify the interelement correction factors every three months by analyzing the interference check solution. The correction factors are calculated according to the instrument manufacturer's directions. If the interelement correction factors are used properly, no false Cr should be detected.
9.1.4.3Negative results with an absolute value greater than three (3) times the detection limit are usually the results of the background correction position being set incorrectly. Scan the spectral region to ensure that the correction position has not been placed on an interfering peak.
9.1.5ICP Duplicate Sample Analysis. Perform one duplicate sample analysis for each compliance sample batch (3 runs).
9.1.5.1As there is no sample preparation required for the ICP analysis, a duplicate analysis is defined as a repeat analysis of one of the field samples. The selected sample shall be analyzed using the same procedures that were used to analyze the original sample.
9.1.5.2Duplicate sample analyses shall agree within 10 percent of the original measurement value.
9.1.5.3Report the original analysis value for the sample and report the duplicate analysis value as the QC check value. If agreement is not achieved, perform the duplicate analysis again. If agreement is not achieved the second time, perform corrective action to identify and correct the problem before analyzing the sample for a third time.
9.1.6ICP Matrix Spiking. Spiked samples shall be prepared and analyzed daily to ensure that there are no matrix effects, that samples and standards have been matrix-matched, and that the laboratory equipment is operating properly.
9.1.6.1Spiked sample recovery analyses should indicate a recovery for the Cr spike of between 75 and 125 percent.
9.1.6.2Cr levels in the spiked sample should provide final solution concentrations that are within the linear portion of the calibration curve, as well as, at a concentration level at least: equal to that of the original sample; and, ten (10) times the detection limit.
9.1.6.3If the spiked sample concentration meets the stated criteria but exceeds the linear calibration range, the spiked sample must be diluted with the field absorbing solution.
9.1.6.4If the recoveries for the Cr spiked samples do not meet the specified criteria, perform corrective action to identify and correct the problem prior to reanalyzing the samples.
9.1.7ICP Field Reagent Blank.
9.1.7.1Analyze a minimum of one matrix-matched field reagent blank (Section 8.2.4) per sample batch to determine if contamination or memory effects are occurring.
9.1.7.2If contamination or memory effects are observed, perform corrective action to identify and correct the problem before reanalyzing the samples.
9.2GFAAS Quality Control.
9.2.1GFAAS Calibration Reference Standards. The calibration curve must be verified by using at least one calibration reference standard (made from a reference material or other independent standard material) at or near the mid-range of the calibration curve.
9.2.1.1The calibration curve must be validated before sample analyses are performed.
9.2.1.2The calibration reference standard must be measured within 10 percent of its true value for the curve to be considered valid.
9.2.2GFAAS Continuing Check Standard.
9.2.2.1Perform analysis of the check standard with the field samples as described in Section 11.4 (at least after every 10 samples, and at the end of the analytical run).
9.2.2.2These standards are analyzed, in part, to monitor the life and performance of the graphite tube. Lack of reproducibility or a significant change in the signal for the check standard may indicate that the graphite tube should be replaced.
9.2.2.3The check standard may be either the mid-range calibration standard or the reference standard.
9.2.2.4The results of the check standard shall agree within 10 percent of the expected value.
9.2.2.5If not, terminate the analyses, correct the problem, recalibrate the instrument, and reanalyze all samples analyzed subsequent to the last acceptable check standard analysis.
9.2.3GFAAS Calibration Blank.
9.2.3.1Perform analysis of the calibration blank with the field samples as described in Section 11.4 (at least after every 10 samples, and at the end of the analytical run).
9.2.3.2The calibration blank is analyzed to monitor the life and performance of the graphite tube as well as the existence of any memory effects. Lack of reproducibility or a significant change in the signal, may indicate that the graphite tube should be replaced.
9.2.3.3The results of the calibration blank shall agree within three standard deviations of the mean blank value.
9.2.3.4If not, analyze the calibration blank two more times and average the results. If the average is not within three standard deviations of the background mean, terminate the analyses, correct the problem, recalibrate, and reanalyze all samples analyzed subsequent to the last acceptable calibration blank analysis.
9.2.4GFAAS Duplicate Sample Analysis. Perform one duplicate sample analysis for each compliance sample batch (3 runs).
9.2.4.1A digested aliquot of the selected sample is processed and analyzed using the identical procedures that were used for the whole sample preparation and analytical efforts.
9.2.4.2Duplicate sample analyses results incorporating duplicate digestions shall agree within 20 percent for sample results exceeding ten (10) times the detection limit.
9.2.4.3Report the original analysis value for the sample and report the duplicate analysis value as the QC check value.
9.2.4.4If agreement is not achieved, perform the duplicate analysis again. If agreement is not achieved the second time, perform corrective action to identify and correct the problem before analyzing the sample for a third time.
9.2.5GFAAS Matrix Spiking.
9.2.5.1Spiked samples shall be prepared and analyzed daily to ensure that (1) correct procedures are being followed, (2) there are no matrix effects and (3) all equipment is operating properly.
9.2.5.2Cr spikes are added prior to any sample preparation.
9.2.5.3Cr levels in the spiked sample should provide final solution concentrations that are within the linear portion of the calibration curve, as well as, at a concentration level at least: equal to that of the original sample; and, ten (10) times the detection limit.
9.2.5.4Spiked sample recovery analyses should indicate a recovery for the Cr spike of between 75 and 125 percent.
9.2.5.5If the recoveries for the Cr spiked samples do not meet the specified criteria, perform corrective action to identify and correct the problem prior to reanalyzing the samples.
9.2.6GFAAS Method of Standard Additions.
9.2.6.1Method of Standard Additions. Perform procedures in Section 5.4 of Method 12 (40 CFR part 60, appendix A)
9.2.6.2Whenever sample matrix problems are suspected and standard/sample matrix matching is not possible or whenever a new sample matrix is being analyzed, perform referenced procedures to determine if the method of standard additions is necessary.
9.2.7GFAAS Field Reagent Blank.
9.2.7.1Analyze a minimum of one matrix-matched field reagent blank (Section 8.2.4) per sample batch to determine if contamination or memory effects are occurring.
9.2.7.2 If contamination or memory effects are observed, perform corrective action to identify and correct the problem before reanalyzing the samples.
9.3IC/PCR Quality Control.
9.3.1IC/PCR Calibration Reference Standards.
9.3.1.1Prepare a calibration reference standard at a concentration that is at or near the mid-point of the calibration curve using the same alkaline matrix as the calibration standards. This reference standard should be prepared from a different Cr stock solution than that used to prepare the calibration curve standards. The reference standard is used to verify the accuracy of the calibration curve.
9.3.1.2The curve must be validated before sample analyses are performed. Prior to sample analysis, analyze at least one reference standard with an expected value within the calibration range.
9.3.1.3The results of this reference standard analysis must be within 10 percent of the true value of the reference standard for the calibration curve to be considered valid.
9.3.2IC/PCR Continuing Check Standard and Calibration Blank.
9.3.2.1Perform analysis of the check standard and the calibration blank with the field samples as described in Section 11.6 (at least after every 10 samples, and at the end of the analytical run).
9.3.2.2The result from the check standard must be within 10 percent of the expected value.
9.3.2.3If the 10 percent criteria is exceeded, excessive drift and/or instrument degradation may have occurred, and must be corrected before further analyses can be performed.
9.3.2.4The results of the calibration blank analyses must agree within three standard deviations of the mean blank value.
9.3.2.5If not, analyze the calibration blank two more times and average the results.
9.3.2.6If the average is not within three standard deviations of the background mean, terminate the analyses, correct the problem, recalibrate, and reanalyze all samples analyzed subsequent to the last acceptable calibration blank analysis.
9.3.3IC/PCR Duplicate Sample Analysis.
9.3.3.1Perform one duplicate sample analysis for each compliance sample batch (3 runs).
9.3.3.2An aliquot of the selected sample is prepared and analyzed using procedures identical to those used for the emission samples (for example, filtration and/or, if necessary, preconcentration).
9.3.3.3Duplicate sample injection results shall agree within 10 percent for sample results exceeding ten (10) times the detection limit.
9.3.3.4Report the original analysis value for the sample and report the duplicate analysis value as the QC check value.
9.3.3.5If agreement is not achieved, perform the duplicate analysis again.
9.3.3.6If agreement is not achieved the second time, perform corrective action to identify and correct the problem prior to analyzing the sample for a third time.
9.3.4ICP/PCR Matrix Spiking. Spiked samples shall be prepared and analyzed with each sample set to ensure that there are no matrix effects, that samples and standards have been matrix-matched, and that the equipment is operating properly.
9.3.4.1Spiked sample recovery analysis should indicate a recovery of the Cr 6 spike between 75 and 125 percent.
9.3.4.2The spiked sample concentration should be within the linear portion of the calibration curve and should be equal to or greater than the concentration of the original sample. In addition, the spiked sample concentration should be at least ten (10) times the detection limit.
9.3.4.3If the recoveries for the Cr 6 spiked samples do not meet the specified criteria, perform corrective action to identify and correct the problem prior to reanalyzing the samples.
9.3.5IC/PCR Field Reagent Blank.
9.3.5.1Analyze a minimum of one matrix-matched field reagent blank (Section 8.2.4) per sample batch to determine if contamination or memory effects are occurring.
9.3.5.2If contamination or memory effects are observed, perform corrective action to identify and correct the problem before reanalyzing the samples.
10.0Calibration and Standardization
10.1Sampling Train Calibration. Perform calibrations described in Method 5, (40 CFR part 60, appendix A). The alternate calibration procedures described in Method 5, may also be used.
10.2ICP Calibration.
10.2.1Calibrate the instrument according to the instrument manufacturer's recommended procedures, using a calibration blank and three standards for the initial calibration.
10.2.2Calibration standards should be prepared fresh daily, as described in Section 7.3.8. Be sure that samples and calibration standards are matrix matched. Flush the system with the calibration blank between each standard.
10.2.3Use the average intensity of multiple exposures (3 or more) for both standardization and sample analysis to reduce random error.
10.2.4Employing linear regression, calculate the correlation coefficient .
10.2.5The correlation coefficient must equal or exceed 0.995.
10.2.6If linearity is not acceptable, prepare and rerun another set of calibration standards or reduce the range of the calibration standards, as necessary.
10.3GFAAS Calibration.
10.3.1For instruments that measure directly in concentration, set the instrument software to display the correct concentration, if applicable.
10.3.2Curve must be linear in order to correctly perform the method of standard additions which is customarily performed automatically with most instrument computer-based data systems.
10.3.3The calibration curve (direct calibration or standard additions) must be prepared daily with a minimum of a calibration blank and three standards that are prepared fresh daily.
10.3.4The calibration curve acceptance criteria must equal or exceed 0.995.
10.3.5If linearity is not acceptable, prepare and rerun another set of calibration standards or reduce the range of calibration standards, as necessary.
10.4IC/PCR Calibration.
10.4.1Prepare a calibration curve using the calibration blank and three calibration standards prepared fresh daily as described in Section 7.3.8.
10.4.2The calibration curve acceptance criteria must equal or exceed 0.995.
10.4.3If linearity is not acceptable, remake and/or rerun the calibration standards. If the calibration curve is still unacceptable, reduce the range of the curve.
10.4.4Analyze the standards with the field samples as described in Section 11.6.
11.0Analytical Procedures
Note:
The method determines the chromium concentration in µg Cr/mL. It is important that the analyst measure the field sample volume prior to analyzing the sample. This will allow for conversion of µg Cr/mL to µg Cr/sample.
11.1ICP Sample Preparation.
11.1.1The ICP analysis is performed directly on the alkaline impinger solution; acid digestion is not necessary, provided the samples and standards are matrix matched.
11.1.2The ICP analysis should only be employed when the solution analyzed has a Cr concentration greater than 35 µg/L or five times the method detection limit as determined according to appendix B in 40 CFR part 136 or by other commonly accepted analytical procedures.
11.2ICP Sample Analysis.
11.2.1The ICP analysis is applicable for the determination of total chromium only.
11.2.2ICP Blanks. Two types of blanks are required for the ICP analysis.
11.2.2.1Calibration Blank. The calibration blank is used in establishing the calibration curve. For the calibration blank, use either 0.1 N NaOH or 0.1 N NaHCO3, whichever is used for the impinger absorbing solution. The calibration blank can be prepared fresh in the laboratory; it does not have to be prepared from the same batch of solution that was used in the field. A sufficient quantity should be prepared to flush the system between standards and samples.
11.2.2.2Field Reagent Blank. The field reagent blank is collected in the field during the testing program. The field reagent blank (Section 8.2.4) is an aliquot of the absorbing solution prepared in Section 7.1.2. The reagent blank is used to assess possible contamination resulting from sample processing.
11.2.3ICP Instrument Adjustment.
11.2.3.1Adjust the ICP instrument for proper operating parameters including wavelength, background correction settings (if necessary), and interfering element correction settings (if necessary).
11.2.3.2The instrument must be allowed to become thermally stable before beginning measurements (usually requiring at least 30 min of operation prior to calibration). During this warmup period, the optical calibration and torch position optimization may be performed (consult the operator's manual).
11.2.4ICP Instrument Calibration.
11.2.4.1Calibrate the instrument according to the instrument manufacturer's recommended procedures, and the procedures specified in Section 10.2.
11.2.4.2Prior to analyzing the field samples, reanalyze the highest calibration standard as if it were a sample.
11.2.4.3Concentration values obtained should not deviate from the actual values or from the established control limits by more than 5 percent, whichever is lower (see Sections 9.1 and 10.2).
11.2.4.4If they do, follow the recommendations of the instrument manufacturer to correct the problem.
11.2.5ICP Operational Quality Control Procedures.
11.2.5.1Flush the system with the calibration blank solution for at least 1 min before the analysis of each sample or standard.
11.2.5.2Analyze the continuing check standard and the calibration blank after each batch of 10 samples.
11.2.5.3Use the average intensity of multiple exposures for both standardization and sample analysis to reduce random error.
11.2.6ICP Sample Dilution.
11.2.6.1Dilute and reanalyze samples that are more concentrated than the linear calibration limit or use an alternate, less sensitive Cr wavelength for which quality control data have already been established.
11.2.6.2When dilutions are performed, the appropriate factors must be applied to sample measurement results.
11.2.7Reporting Analytical Results. All analytical results should be reported in µg Cr/mL using three significant figures. Field sample volumes (mL) must be reported also.
11.3GFAAS Sample Preparation.
11.3.1GFAAS Acid Digestion. An acid digestion of the alkaline impinger solution is required for the GFAAS analysis.
11.3.1.1In a beaker, add 10 mL of concentrated HNO3 to a 100 mL sample aliquot that has been well mixed. Cover the beaker with a watch glass. Place the beaker on a hot plate and reflux the sample to near dryness. Add another 5 mL of concentrated HNO3 to complete the digestion. Again, carefully reflux the sample volume to near dryness. Rinse the beaker walls and watch glass with reagent water.
11.3.1.2The final concentration of HNO3 in the solution should be 1 percent (v/v).
11.3.1.3Transfer the digested sample to a 50-mL volumetric flask. Add 0.5 mL of concentrated HNO3 and 1 mL of the 10 µg/mL of Ca(NO3)2. Dilute to 50 mL with reagent water.
11.3.2HNO3 Concentration. A different final volume may be used based on the expected Cr concentration, but the HNO3 concentration must be maintained at 1 percent (v/v).
11.4GFAAS Sample Analysis.
11.4.1The GFAAS analysis is applicable for the determination of total chromium only.
11.4.2GFAAS Blanks. Two types of blanks are required for the GFAAS analysis.
11.4.2.1Calibration Blank. The 1.0 percent HNO3 is the calibration blank which is used in establishing the calibration curve.
11.4.2.2Field Reagent Blank. An aliquot of the 0.1 N NaOH solution or the 0.1 N NaHCO3 prepared in Section 7.1.2 is collected for the field reagent blank. The field reagent blank is used to assess possible contamination resulting from processing the sample.
11.4.2.2.1The reagent blank must be subjected to the entire series of sample preparation and analytical procedures, including the acid digestion.
11.4.2.2.2The reagent blank's final solution must contain the same acid concentration as the sample solutions.
11.4.3GFAAS Instrument Adjustment.
11.4.3.1The 357.9 nm wavelength line shall be used.
11.4.3.2Follow the manufacturer's instructions for all other spectrophotometer operating parameters.
11.4.4Furnace Operational Parameters. Parameters suggested by the manufacturer should be employed as guidelines.
11.4.4.1Temperature-sensing mechanisms and temperature controllers can vary between instruments and/or with time; the validity of the furnace operating parameters must be periodically confirmed by systematically altering the furnace parameters while analyzing a standard. In this manner, losses of analyte due to higher-than-necessary temperature settings or losses in sensitivity due to less than optimum settings can be minimized.
11.4.4.2Similar verification of furnace operating parameters may be required for complex sample matrices (consult instrument manual for additional information). Calibrate the GFAAS system following the procedures specified in Section 10.3.
11.4.5GFAAS Operational Quality Control Procedures.
11.4.5.1Introduce a measured aliquot of digested sample into the furnace and atomize.
11.4.5.2If the measured concentration exceeds the calibration range, the sample should be diluted with the calibration blank solution (1.0 percent HNO3) and reanalyzed.
11.4.5.3Consult the operator's manual for suggested injection volumes. The use of multiple injections can improve accuracy and assist in detecting furnace pipetting errors.
11.4.5.4Analyze a minimum of one matrix-matched reagent blank per sample batch to determine if contamination or any memory effects are occurring.
11.4.5.5Analyze a calibration blank and a continuing check standard after approximately every batch of 10 sample injections.
11.4.6GFAAS Sample Dilution.
11.4.6.1Dilute and reanalyze samples that are more concentrated than the instrument calibration range.
11.4.6.2If dilutions are performed, the appropriate factors must be applied to sample measurement results.
11.4.7Reporting Analytical Results.
11.4.7.1Calculate the Cr concentrations by the method of standard additions (see operator's manual) or, from direct calibration. All dilution and/or concentration factors must be used when calculating the results.
11.4.7.2Analytical results should be reported in µg Cr/mL using three significant figures. Field sample volumes (mL) must be reported also.
11.5IC/PCR Sample Preparation.
11.5.1Sample pH. Measure and record the sample pH prior to analysis.
11.5.2Sample Filtration. Prior to preconcentration and/or analysis, filter all field samples through a 0.45-µm filter. The filtration step should be conducted just prior to sample injection/analysis.
11.5.2.1Use a portion of the sample to rinse the syringe filtration unit and acetate filter and then collect the required volume of filtrate.
11.5.2.2Retain the filter if total Cr is to be determined also.
11.5.3Sample Preconcentration (older instruments).
11.5.3.1For older instruments, a preconcentration system may be used in conjunction with the IC/PCR to increase sensitivity for trace levels of Cr 6.
11.5.3.2The preconcentration is accomplished by selectively retaining the analyte on a solid absorbent, followed by removal of the analyte from the absorbent (consult instrument manual).
11.5.3.3For a manual system, position the injection valve so that the eluent displaces the concentrated Cr 6 sample, transferring it from the preconcentration column and onto the IC anion separation column.
11.6IC/PCR Sample Analyses.
11.6.1The IC/PCR analysis is applicable for hexavalent chromium measurements only.
11.6.2IC/PCR Blanks. Two types of blanks are required for the IC/PCR analysis.
11.6.2.1Calibration Blank. The calibration blank is used in establishing the analytical curve. For the calibration blank, use either 0.1 N NaOH or 0.1 N NaHCO3, whichever is used for the impinger solution. The calibration blank can be prepared fresh in the laboratory; it does not have to be prepared from the same batch of absorbing solution that is used in the field.
11.6.2.2Field Reagent Blank. An aliquot of the 0.1 N NaOH solution or the 0.1 N NaHCO3 solution prepared in Section 7.1.2 is collected for the field reagent blank. The field reagent blank is used to assess possible contamination resulting from processing the sample.
11.6.3Stabilized Baseline. Prior to sample analysis, establish a stable baseline with the detector set at the required attenuation by setting the eluent and post-column reagent flow rates according to the manufacturers recommendations.
Note:
As long as the ratio of eluent flow rate to PCR flow rate remains constant, the standard curve should remain linear. Inject a sample of reagent water to ensure that no Cr 6 appears in the water blank.
11.6.4Sample Injection Loop. Size of injection loop is based on standard/sample concentrations and the selected attenuator setting.
11.6.4.1A 50-µL loop is normally sufficient for most higher concentrations.
11.6.4.2The sample volume used to load the injection loop should be at least 10 times the loop size so that all tubing in contact with the sample is thoroughly flushed with the new sample to prevent cross contamination.
11.6.5IC/PCR Instrument Calibration.
11.6.5.1First, inject the calibration standards prepared, as described in Section 7.3.8 to correspond to the appropriate concentration range, starting with the lowest standard first.
11.6.5.2Check the performance of the instrument and verify the calibration using data gathered from analyses of laboratory blanks, calibration standards, and a quality control sample.
11.6.5.3Verify the calibration by analyzing a calibration reference standard. If the measured concentration exceeds the established value by more than 10 percent, perform a second analysis. If the measured concentration still exceeds the established value by more than 10 percent, terminate the analysis until the problem can be identified and corrected.
11.6.6IC/PCR Instrument Operation.
11.6.6.1Inject the calibration reference standard (as described in Section 9.3.1), followed by the field reagent blank (Section 8.2.4), and the field samples.
11.6.6.1.1Standards (and QC standards) and samples are injected into the sample loop of the desired size (use a larger size loop for greater sensitivity). The Cr 6 is collected on the resin bed of the column.
11.6.6.1.2After separation from other sample components, the Cr 6 forms a specific complex in the post-column reactor with the DPC reaction solution, and the complex is detected by visible absorbance at a maximum wavelength of 540 nm.
11.6.6.1.3The amount of absorbance measured is proportional to the concentration of the Cr 6 complex formed.
11.6.6.1.4The IC retention time and the absorbance of the Cr 6 complex with known Cr 6 standards analyzed under identical conditions must be compared to provide both qualitative and quantitative analyses.
11.6.6.1.5If a sample peak appears near the expected retention time of the Cr 6 ion, spike the sample according to Section 9.3.4 to verify peak identity.
11.6.7IC/PCR Operational Quality Control Procedures.
11.6.7.1Samples should be at a pH ≥8.5 for NaOH and ≥8.0 if using NaHCO3; document any discrepancies.
11.6.7.2Refrigerated samples should be allowed to equilibrate to ambient temperature prior to preparation and analysis.
11.6.7.3Repeat the injection of the calibration standards at the end of the analytical run to assess instrument drift. Measure areas or heights of the Cr 6/DPC complex chromatogram peaks.
11.6.7.4To ensure the precision of the sample injection (manual or autosampler), the response for the second set of injected standards must be within 10 percent of the average response.
11.6.7.5If the 10 percent criteria duplicate injection cannot be achieved, identify the source of the problem and rerun the calibration standards.
11.6.7.6Use peak areas or peak heights from the injections of calibration standards to generate a linear calibration curve. From the calibration curve, determine the concentrations of the field samples.
11.6.8IC/PCR Sample Dilution.
11.6.8.1Samples having concentrations higher than the established calibration range must be diluted into the calibration range and re-analyzed.
11.6.8.2If dilutions are performed, the appropriate factors must be applied to sample measurement results.
11.6.9Reporting Analytical Results. Results should be reported in µg Cr 6/mL using three significant figures. Field sample volumes (mL) must be reported also.
12.0Data Analysis and Calculations
12.1Pretest Calculations.
12.1.1Pretest Protocol (Site Test Plan).
12.1.1.1The pretest protocol should define and address the test data quality objectives (DQOs), with all assumptions, that will be required by the end user (enforcement authority); what data are needed? why are the data needed? how will the data be used? what are method detection limits? and what are estimated target analyte levels for the following test parameters.
12.1.1.1.1Estimated source concentration for total chromium and/or Cr 6.
12.1.1.1.2Estimated minimum sampling time and/or volume required to meet method detection limit requirements (Appendix B 40 CFR part 136) for measurement of total chromium and/or Cr 6.
12.1.1.1.3Demonstrate that planned sampling parameters will meet DQOs. The protocol must demonstrate that the planned sampling parameters calculated by the tester will meet the needs of the source and the enforcement authority.
12.1.1.2The pre-test protocol should include information on equipment, logistics, personnel, process operation, and other resources necessary for an efficient and coordinated test.
12.1.1.3At a minimum, the pre-test protocol should identify and be approved by the source, the tester, the analytical laboratory, and the regulatory enforcement authority. The tester should not proceed with the compliance testing before obtaining approval from the enforcement authority.
12.1.2Post Test Calculations.
12.1.2.1Perform the calculations, retaining one extra decimal figure beyond that of the acquired data. Round off figures after final calculations.
12.1.2.2Nomenclature.
CS = Concentration of Cr in sample solution, µg Cr/mL.
Ccr = Concentration of Cr in stack gas, dry basis, corrected to standard conditions, mg/dscm.
D = Digestion factor, dimension less.
F = Dilution factor, dimension less.
MCr = Total Cr in each sample, µg.
Vad = Volume of sample aliquot after digestion, mL.
Vaf = Volume of sample aliquot after dilution, mL.
Vbd = Volume of sample aliquot submitted to digestion, mL.
Vbf = Volume of sample aliquot before dilution, mL.
VmL = Volume of impinger contents plus rinses, mL.
Vm(std) = Volume of gas sample measured by the dry gas meter, corrected to standard conditions, dscm.
12.1.2.3Dilution Factor. The dilution factor is the ratio of the volume of sample aliquot after dilution to the volume before dilution. This ratio is given by the following equation:
12.1.2.4Digestion Factor. The digestion factor is the ratio of the volume of sample aliquot after digestion to the volume before digestion. This ratio is given by Equation 306-2.
12.1.2.5Total Cr in Sample. Calculate MCr, the total µg Cr in each sample, using the following equation:
12.1.2.6Average Dry Gas Meter Temperature and Average Orifice Pressure Drop. Same as Method 5.
12.1.2.7Dry Gas Volume, Volume of Water Vapor, Moisture Content. Same as Method 5.
12.1.2.8Cr Emission Concentration (CCr). Calculate CCr, the Cr concentration in the stack gas, in mg/dscm on a dry basis, corrected to standard conditions using the following equation:
12.1.2.9Isokinetic Variation, Acceptable Results. Same as Method 5.
13.0Method Performance
13.1Range. The recommended working range for all of the three analytical techniques starts at five times the analytical detection limit (see also Section 13.2.2). The upper limit of all three techniques can be extended indefinitely by appropriate dilution.
13.2Sensitivity.
13.2.1Analytical Sensitivity. The estimated instrumental detection limits listed are provided as a guide for an instrumental limit. The actual method detection limits are sample and instrument dependent and may vary as the sample matrix varies.
13.2.1.2ICP Analytical Sensitivity. The minimum estimated detection limits for ICP, as reported in Method 6010A and the recently revised Method 6010B of SW-846 (Reference 1), are 7.0 µg Cr/L and 4.7 µg Cr/L, respectively.
13.2.1.3GFAAS Analytical Sensitivity. The minimum estimated detection limit for GFAAS, as reported in Methods 7000A and 7191 of SW-846 (Reference 1), is 1 µg Cr/L.
13.2.1.4IC/PCR Analytical Sensitivity. The minimum detection limit for IC/PCR with a preconcentrator, as reported in Methods 0061 and 7199 of SW-846 (Reference 1), is 0.05 µg Cr 6/L.
1.3.2.1.5Determination of Detection Limits. The laboratory performing the Cr 6 measurements must determine the method detection limit on a quarterly basis using a suitable procedure such as that found in 40 CFR, part 136, appendix B. The determination should be made on samples in the appropriate alkaline matrix. Normally this involves the preparation (if applicable) and consecutive measurement of seven (7) separate aliquots of a sample with a concentration <5 times the expected detection limit. The detection limit is 3.14 times the standard deviation of these results.
13.2.2In-stack Sensitivity. The in-stack sensitivity depends upon the analytical detection limit, the volume of stack gas sampled, the total volume of the impinger absorbing solution plus the rinses, and, in some cases, dilution or concentration factors from sample preparation. Using the analytical detection limits given in Sections 13.2.1.1, 13.2.1.2, and 13.2.1.3; a stack gas sample volume of 1.7 dscm; a total liquid sample volume of 500 mL; and the digestion concentration factor of 1/2 for the GFAAS analysis; the corresponding in-stack detection limits are 0.0014 mg Cr/dscm to 0.0021 mg Cr/dscm for ICP, 0.00015 mg Cr/dscm for GFAAS, and 0.000015 mg Cr 6/dscm for IC/PCR with preconcentration.
Note:
It is recommended that the concentration of Cr in the analytical solutions be at least five times the analytical detection limit to optimize sensitivity in the analyses. Using this guideline and the same assumptions for impinger sample volume, stack gas sample volume, and the digestion concentration factor for the GFAAS analysis (500 mL,1.7 dscm, and 1/2, respectively), the recommended minimum stack concentrations for optimum sensitivity are 0.0068 mg Cr/dscm to 0.0103 mg Cr/dscm for ICP, 0.00074 mg Cr/dscm for GFAAS, and 0.000074 mg Cr 6/dscm for IC/PCR with preconcentration. If required, the in-stack detection limits can be improved by either increasing the stack gas sample volume, further reducing the volume of the digested sample for GFAAS, improving the analytical detection limits, or any combination of the three.
13.3Precision.
13.3.1The following precision data have been reported for the three analytical methods. In each case, when the sampling precision is combined with the reported analytical precision, the resulting overall precision may decrease.
13.3.2Bias data is also reported for GFAAS.
13.4ICP Precision.
13.4.1As reported in Method 6010B of SW-846 (Reference 1), in an EPA round-robin Phase 1 study, seven laboratories applied the ICP technique to acid/distilled water matrices that had been spiked with various metal concentrates. For true values of 10, 50, and 150 µg Cr/L; the mean reported values were 10, 50, and 149 µg Cr/L; and the mean percent relative standard deviations were 18, 3.3, and 3.8 percent, respectively.
13.4.2In another multi laboratory study cited in Method 6010B, a mean relative standard of 8.2 percent was reported for an aqueous sample concentration of approximately 3750 µg Cr/L.
13.5GFAAS Precision. As reported in Method 7191 of SW-846 (Reference 1), in a single laboratory (EMSL), using Cincinnati, Ohio tap water spiked at concentrations of 19, 48, and 77 µg Cr/L, the standard deviations were ±0.1, ±0.2, and ±0.8, respectively. Recoveries at these levels were 97 percent, 101 percent, and 102 percent, respectively.
13.6IC/PCR Precision. As reported in Methods 0061 and 7199 of SW-846 (Reference 1), the precision of IC/PCR with sample preconcentration is 5 to 10 percent. The overall precision for sewage sludge incinerators emitting 120 ng/dscm of Cr 6 and 3.5 µg/dscm of total Cr was 25 percent and 9 percent, respectively; and for hazardous waste incinerators emitting 300 ng/dscm of C 6 the precision was 20 percent.
14.0Pollution Prevention
14.1The only materials used in this method that could be considered pollutants are the chromium standards used for instrument calibration and acids used in the cleaning of the collection and measurement containers/labware, in the preparation of standards, and in the acid digestion of samples. Both reagents can be stored in the same waste container.
14.2Cleaning solutions containing acids should be prepared in volumes consistent with use to minimize the disposal of excessive volumes of acid.
14.3To the extent possible, the containers/vessels used to collect and prepare samples should be cleaned and reused to minimize the generation of solid waste.
15.0Waste Management
15.1It is the responsibility of the laboratory and the sampling team to comply with all federal, state, and local regulations governing waste management, particularly the discharge regulations, hazardous waste identification rules, and land disposal restrictions; and to protect the air, water, and land by minimizing and controlling all releases from field operations.
15.2For further information on waste management, consult The Waste Management Manual for Laboratory Personnel and Less is Better—Laboratory Chemical Management for Waste Reduction, available from the American Chemical Society's Department of Government Relations and Science Policy, 1155 16th Street NW, Washington, DC 20036.
16.0References
1. “Test Methods for Evaluating Solid Waste, Physical/Chemical Methods, SW-846, Third Edition,” as amended by Updates I, II, IIA, IIB, and III. Document No. 955-001-000001. Available from Superintendent of Documents, U.S. Government Printing Office, Washington, DC, November 1986.
2. Cox, X.B., R.W. Linton, and F.E. Butler. Determination of Chromium Speciation in Environmental Particles—A Multi-technique Study of Ferrochrome Smelter Dust. Accepted for publication in Environmental Science and Technology.
3. Same as Section 17.0 of Method 5, References 2, 3, 4, 5, and 7.
4. California Air Resources Board, “Determination of Total Chromium and Hexavalent Chromium Emissions from Stationary Sources.” Method 425, September 12, 1990.
5. The Merck Index. Eleventh Edition. Merck & Co., Inc., 1989.
6. Walpole, R.E., and R.H. Myers. “Probability and Statistics for Scientists and Engineering.” 3rd Edition. MacMillan Publishing Co., NewYork, N.Y., 1985.
17.0Tables, Diagrams, Flowcharts, and Validation Data
Method 306A—Determination of Chromium Emissions From Decorative and Hard Chromium Electroplating and Chromium Anodizing Operations
Note:
This method does not include all of the specifications (e.g., equipment and supplies) and procedures (e.g., sampling and analytical) essential to its performance. Some material is incorporated by reference from other methods in 40 CFR part 60, appendix A and in this part. Therefore, to obtain reliable results, persons using this method should have a thorough knowledge of at least Methods 5 and 306.
1.0Scope and Application
1.1Analyte. Chromium. CAS Number (7440-47-3).
1.2Applicability.
1.2.1This method applies to the determination of chromium (Cr) in emissions from decorative and hard chromium electroplating facilities, chromium anodizing operations, and continuous chromium plating at iron and steel facilities. The method is less expensive and less complex to conduct than Method 306. Correctly applied, the precision and bias of the sample results should be comparable to those obtained with the isokinetic Method 306. This method is applicable for the determination of air emissions under nominal ambient moisture, temperature, and pressure conditions.
1.2.2The method is also applicable to electroplating and anodizing sources controlled by wet scrubbers.
1.3Data Quality Objectives.
1.3.1Pretest Protocol.
1.3.1.1The pretest protocol should define and address the test data quality objectives (DQOs), with all assumptions, that will be required by the end user (enforcement authority); what data are needed? why are the data needed? how will data be used? what are method detection limits? and what are estimated target analyte levels for the following test parameters.
1.3.1.1.1Estimated source concentration for total chromium and/or Cr 6.
1.3.1.1.2Estimated minimum sampling time and/or volume required to meet method detection limit requirements (appendix B 40 CFR part 136) for measurement of total chromium and/or Cr 6.
1.3.1.1.3Demonstrate that planned sampling parameters will meet DQOs. The protocol must demonstrate that the planned sampling parameters calculated by the tester will meet the needs of the source and the enforcement authority.
1.3.1.2The pre-test protocol should include information on equipment, logistics, personnel, process operation, and other resources necessary for an efficient and coordinated performance test.
1.3.1.3At a minimum, the pre-test protocol should identify and be approved by the source, the tester, the analytical laboratory, and the regulatory enforcement authority. The tester should not proceed with the compliance testing before obtaining approval from the enforcement authority.
2.0Summary of Method
2.1Sampling.
2.1.1An emission sample is extracted from the source at a constant sampling rate determined by a critical orifice and collected in a sampling train composed of a probe and impingers. The proportional sampling time at the cross sectional traverse points is varied according to the stack gas velocity at each point. The total sample time must be at least two hours.
2.1.2The chromium emission concentration is determined by the same analytical procedures described in Method 306: inductively-coupled plasma emission spectrometry (ICP), graphite furnace atomic absorption spectrometry (GFAAS), or ion chromatography with a post-column reactor (IC/PCR).
2.1.2.1Total chromium samples with high chromium concentrations (≥35 µg/L) may be analyzed using inductively coupled plasma emission spectrometry (ICP) at 267.72 nm.
Note:
The ICP analysis is applicable for this method only when the solution analyzed has a Cr concentration greater than or equal to 35 µg/L or five times the method detection limit as determined according to Appendix B in 40 CFR part 136.
2.1.2.2Alternatively, when lower total chromium concentrations (<35 µg/L) are encountered, a portion of the alkaline sample solution may be digested with nitric acid and analyzed by graphite furnace atomic absorption spectroscopy (GFAAS) at 357.9 nm.
2.1.2.3If it is desirable to determine hexavalent chromium (Cr 6) emissions, the samples may be analyzed using an ion chromatograph equipped with a post-column reactor (IC/PCR) and a visible wavelength detector. To increase sensitivity for trace levels of Cr 6, a preconcentration system may be used in conjunction with the IC/PCR.
3.0Definitions
3.1Total Chromium—measured chromium content that includes both major chromium oxidation states (Cr 3, Cr 6).
3.2May—Implies an optional operation.
3.3Digestion—The analytical operation involving the complete (or nearly complete) dissolution of the sample in order to ensure the complete solubilization of the element (analyte) to be measured.
3.4Interferences—Physical, chemical, or spectral phenomena that may produce a high or low bias in the analytical result.
3.5Analytical System—All components of the analytical process including the sample digestion and measurement apparatus.
3.6Sample Recovery—The quantitative transfer of sample from the collection apparatus to the sample preparation (digestion, etc.) apparatus. This term should not be confused with analytical recovery.
4.0Interferences
4.1Same as in Method 306, Section 4.0.
5.0Safety
5.1Disclaimer. This method may involve hazardous materials, operations, and equipment. This test method does not purport to address all of the safety issues associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to performing this test method.
5.2Chromium and some chromium compounds have been listed as carcinogens although Chromium (III) compounds show little or no toxicity. Chromium is a skin and respiratory irritant.
6.0Equipment and Supplies
Note:
Mention of trade names or specific products does not constitute endorsement by the Environmental Protection Agency.
6.1Sampling Train. A schematic of the sampling train is shown in Figure 306A-1. The individual components of the train are available commercially, however, some fabrication and assembly are required.
6.1.1Probe Nozzle/Tubing and Sheath.
6.1.1.1Use approximately 6.4-mm (1/4-in.) inside diameter (ID) glass or rigid plastic tubing approximately 20 cm (8 in.) in length with a short 90 degree bend at one end to form the sampling nozzle. Grind a slight taper on the nozzle end before making the bend. Attach the nozzle to flexible tubing of sufficient length to enable collection of a sample from the stack.
6.1.1.2Use a straight piece of larger diameter rigid tubing (such as metal conduit or plastic water pipe) to form a sheath that begins about 2.5 cm (1 in.) from the 90 ° bend on the nozzle and encases and supports the flexible tubing.
6.1.2 Type S Pitot Tube. Same as Method 2, Section 6.1 (40 CFR part 60, appendix A).
6.1.3Temperature Sensor.
6.1.3.1A thermocouple, liquid-filled bulb thermometer, bimetallic thermometer, mercury-in-glass thermometer, or other sensor capable of measuring temperature to within 1.5 percent of the minimum absolute stack temperature.
6.1.3.2The temperature sensor shall either be positioned near the center of the stack, or be attached to the pitot tube as directed in Section 6.3 of Method 2.
6.1.4Sample Train Connectors.
6.1.4.1Use thick wall flexible plastic tubing (polyethylene, polypropylene, or polyvinyl chloride) ∼ 6.4-mm (1/4-in.) to 9.5-mm (3/8-in.) ID to connect the train components.
6.1.4.2A combination of rigid plastic tubing and thin wall flexible tubing may be used as long as tubing walls do not collapse when leak-checking the train. Metal tubing cannot be used.
6.1.5Impingers. Three, one-quart capacity, glass canning jars with vacuum seal lids, or three Greenburg-Smith (GS) design impingers connected in series, or equivalent, may be used.
6.1.5.1One-quart glass canning jar. Three separate jar containers are required: (1) the first jar contains the absorbing solution; (2) the second is empty and is used to collect any reagent carried over from the first container; and (3) the third contains the desiccant drying agent.
6.1.5.2Canning Jar Connectors. The jar containers are connected by leak-tight inlet and outlet tubes installed in the lids of each container for assembly with the train. The tubes may be made of ∼ 6.4 mm (1/4-in.) ID glass or rigid plastic tubing. For the inlet tube of the first impinger, heat the glass or plastic tubing and draw until the tubing separates. Fabricate the necked tip to form an orifice tip that is approximately 2.4 mm (3/32-in.) ID.
6.1.5.2.1When assembling the first container, place the orifice tip end of the tube approximately 4.8 mm (3/16-in.) above the inside bottom of the jar.
6.1.5.2.2For the second container, the inlet tube need not be drawn and sized, but the tip should be approximately 25 mm (1 in.) above the bottom of the jar.
6.1.5.2.3The inlet tube of the third container should extend to approximately 12.7 mm (1/2-in.) above the bottom of the jar.
6.1.5.2.4Extend the outlet tube for each container approximately 50 mm (2 in.) above the jar lid and downward through the lid, approximately 12.7 mm (1/2-in.) beneath the bottom of the lid.
6.1.5.3Greenburg-Smith Impingers. Three separate impingers of the Greenburg-Smith (GS) design as described in Section 6.0 of Method 5 are required. The first GS impinger shall have a standard tip (orifice/plate), and the second and third GS impingers shall be modified by replacing the orifice/plate tube with a 13 mm (1/2-in.) ID glass tube, having an unrestricted opening located 13 mm (1/2-in.) from the bottom of the outer flask.
6.1.5.4Greenburg-Smith Connectors. The GS impingers shall be connected by leak-free ground glass “U” tube connectors or by leak-free non-contaminating flexible tubing. The first impinger shall contain the absorbing solution, the second is empty and the third contains the desiccant drying agent.
6.1.6Manometer. Inclined/vertical type, or equivalent device, as described in Section 6.2 of Method 2 (40 CFR part 60, appendix A).
6.1.7Critical Orifice. The critical orifice is a small restriction in the sample line that is located upstream of the vacuum pump. The orifice produces a constant sampling flow rate that is approximately 0.021 cubic meters per minute (m3/min) or 0.75 cubic feet per minute (cfm).
6.1.7.1The critical orifice can be constructed by sealing a 2.4-mm (3/32-in.) ID brass tube approximately 14.3 mm (9/16-in.) in length inside a second brass tube that is approximately 8 mm (5/16-in.) ID and 14.3-mm (9/16-in.) in length .
6.1.7.2Materials other than brass can be used to construct the critical orifice as long as the flow through the sampling train can be maintained at approximately 0.021 cubic meter per minute (0.75) cfm.
6.1.8Connecting Hardware. Standard pipe and fittings, 9.5-mm (3/8-in.), 6.4-mm (1/4-in.) or 3.2-mm (1/8-in.) ID, may be used to assemble the vacuum pump, dry gas meter and other sampling train components.
6.1.9Vacuum Gauge. Capable of measuring approximately 760 mm Hg (30 in. Hg) vacuum in 25.4 mm HG (1 in. Hg) increments. Locate vacuum gauge between the critical orifice and the vacuum pump.
6.1.10Pump Oiler. A glass oil reservoir with a wick mounted at the vacuum pump inlet that lubricates the pump vanes. The oiler should be an in-line type and not vented to the atmosphere. See EMTIC Guideline Document No. GD-041.WPD for additional information.
6.1.11Vacuum Pump. Gast Model 0522-V103-G18DX, or equivalent, capable of delivering at least 1.5 cfm at 15 in. Hg vacuum.
6.1.12Oil Trap/Muffler. An empty glass oil reservoir without wick mounted at the pump outlet to control the pump noise and prevent oil from reaching the dry gas meter.
6.1.13By-pass Fine Adjust Valve (Optional). Needle valve assembly 6.4-mm (1/4-in.), Whitey 1 RF 4-A, or equivalent, that allows for adjustment of the train vacuum.
6.1.13.1A fine-adjustment valve is positioned in the optional pump by-pass system that allows the gas flow to recirculate through the pump. This by-pass system allows the tester to control/reduce the maximum leak-check vacuum pressure produced by the pump.
6.1.13.1.1The tester must conduct the post test leak check at a vacuum equal to or greater than the maximum vacuum encountered during the sampling run.
6.1.13.1.2The pump by-pass assembly is not required, but is recommended if the tester intends to leak-check the 306A train at the vacuum experienced during a run.
6.1.14Dry Gas Meter. An Equimeter Model 110 test meter or, equivalent with temperature sensor(s) installed (inlet/outlet) to monitor the meter temperature. If only one temperature sensor is installed, locate the sensor at the outlet side of the meter. The dry gas meter must be capable of measuring the gaseous volume to within ±2% of the true volume.
Note:
The Method 306 sampling train is also commercially available and may be used to perform the Method 306A tests. The sampling train may be assembled as specified in Method 306A with the sampling rate being operated at the delta H@ specified for the calibrated orifice located in the meter box. The Method 306 train is then operated as described in Method 306A.
6.2Barometer. Mercury aneroid barometer, or other barometer equivalent, capable of measuring atmospheric pressure to within ±2.5 mm Hg (0.1 in. Hg).
6.2.1A preliminary check of the barometer shall be made against a mercury-in-glass reference barometer or its equivalent.
6.2.2Tester may elect to obtain the absolute barometric pressure from a nearby National Weather Service station.
6.2.2.1The station value (which is the absolute barometric pressure) must be adjusted for elevation differences between the weather station and the sampling location. Either subtract 2.5 mm Hg (0.1 in. Hg) from the station value per 30 m (100 ft) of elevation increase or add the same for an elevation decrease.
6.2.2.2If the field barometer cannot be adjusted to agree within 0.1 in. Hg of the reference barometric, repair or discard the unit. The barometer pressure measurement shall be recorded on the sampling data sheet.
6.3Sample Recovery. Same as Method 5, Section 6.2 (40 CFR part 60, appendix A), with the following exceptions:
6.3.1Probe-Liner and Probe-Nozzle Brushes. Brushes are not necessary for sample recovery. If a probe brush is used, it must be non-metallic.
6.3.2Wash Bottles. Polyethylene wash bottle, for sample recovery absorbing solution.
6.3.3Sample Recovery Solution. Use 0.1 N NaOH or 0.1 N NaHCO3, whichever is used as the impinger absorbing solution, to replace the acetone.
6.3.4Sample Storage Containers.
6.3.4.1Glass Canning Jar. The first canning jar container of the sampling train may serve as the sample shipping container. A new lid and sealing plastic wrap shall be substituted for the container lid assembly.
6.3.4.2Polyethylene or Glass Containers. Transfer the Greenburg-Smith impinger contents to precleaned polyethylene or glass containers. The samples shall be stored and shipped in 250-mL, 500-mL or 1000-mL polyethylene or glass containers with leak-free, non metal screw caps.
6.3.5pH Indicator Strip, for Cr 6 Samples. pH indicator strips, or equivalent, capable of determining the pH of solutions between the range of 7 and 12, at 0.5 pH increments.
6.3.6Plastic Storage Containers. Air tight containers to store silica gel.
6.4Analysis. Same as Method 306, Section 6.3.
7.0Reagents and Standards.
Note:
Unless otherwise indicated, all reagents shall conform to the specifications established by the Committee on Analytical Reagents of the American Chemical Society (ACS reagent grade). Where such specifications are not available, use the best available grade. It is recommended, but not required, that reagents be checked by the appropriate analysis prior to field use to assure that contamination is below the analytical detection limit for the ICP or GFAAS total chromium analysis; and that contamination is below the analytical detection limit for Cr 6 using IC/PCR for direct injection or, if selected, preconcentration.
7.1Sampling.
7.1.1Water. Reagent water that conforms to ASTM Specification D1193 Type II (incorporated by reference see § 63.14). All references to water in the method refer to reagent water unless otherwise specified. It is recommended that water blanks be checked prior to preparing the sampling reagents to ensure that the Cr content is less than three (3) times the anticipated detection limit of the analytical method.
7.1.2Sodium Hydroxide (NaOH) Absorbing Solution, 0.1 N. Dissolve 4.0 g of sodium hydroxide in 1 liter of water to obtain a pH of approximately 8.5.
7.1.3Sodium Bicarbonate (NaHCO3) Absorbing Solution, 0.1 N. Dissolve approximately 8.5 g of sodium bicarbonate in 1 liter of water to obtain a pH of approximately 8.3.
7.1.4Chromium Contamination.
7.1.4.1The absorbing solution shall not exceed the QC criteria noted in Method 306, Section 7.1.1 (≤3 times the instrument detection limit).
7.1.4.2When the Cr 6 content in the field samples exceeds the blank concentration by at least a factor of ten (10), Cr 6 blank levels ≤10 times the detection limit will be allowed.
Note:
At sources with high concentrations of acids and/or SO2, the concentration of NaOH or NaHCO3 should be ≥0.5 N to insure that the pH of the solution remains at or above 8.5 for NaOH and 8.0 for NaHCO3 during and after sampling.
7.1.3Desiccant. Silica Gel, 6-16 mesh, indicating type. Alternatively, other types of desiccants may be used, subject to the approval of the Administrator.
7.2Sample Recovery. Same as Method 306, Section 7.2.
7.3Sample Preparation and Analysis. Same as Method 306, Section 7.3.
7.4Glassware Cleaning Reagents. Same as Method 306, Section 7.4.
8.0Sample Collection, Recovery, Preservation, Holding Times, Storage, and Transport
Note:
Prior to sample collection, consideration should be given as to the type of analysis (Cr 6 or total Cr) that will be performed. Deciding which analysis will be performed will enable the tester to determine which appropriate sample recovery and storage procedures will be required to process the sample.
8.1Sample Collection.
8.1.1Pretest Preparation.
8.1.1.1Selection of Measurement Site. Locate the sampling ports as specified in Section 11.0 of Method 1 (40 CFR part 60, appendix A).
8.1.1.2Location of Traverse Points.
8.1.1.2.1Locate the traverse points as specified in Section 11.0 of Method 1 (40 CFR part 60, appendix A). Use a total of 24 sampling points for round ducts and 24 or 25 points for rectangular ducts. Mark the pitot and sampling probe to identify the sample traversing points.
8.1.1.2.2For round ducts less than 12 inches in diameter, use a total of 16 points.
8.1.1.3Velocity Pressure Traverse. Perform an initial velocity traverse before obtaining samples. The Figure 306A-2 data sheet may be used to record velocity traverse data.
8.1.1.3.1To demonstrate that the flow rate is constant over several days of testing, perform complete traverses at the beginning and end of each day's test effort, and calculate the deviation of the flow rate for each daily period. The beginning and end flow rates are considered constant if the deviation does not exceed 10 percent. If the flow rate exceeds the 10 percent criteria, either correct the inconsistent flow rate problem, or obtain the Administrator's approval for the test results.
8.1.1.3.2Perform traverses as specified in Section 8.0 of Method 2, but record only the Δp (velocity pressure) values for each sampling point. If a mass emission rate is desired, stack velocity pressures shall be recorded before and after each test, and an average stack velocity pressure determined for the testing period.
8.1.1.4Verification of Absence of Cyclonic Flow. Check for cyclonic flow during the initial traverse to verify that it does not exist. Perform the cyclonic flow check as specified in Section 11.4 of Method 1 (40 CFR part 60, appendix A).
8.1.1.4.1If cyclonic flow is present, verify that the absolute average angle of the tangential flow does not exceed 20 degrees. If the average value exceeds 20 degrees at the sampling location, the flow condition in the stack is unacceptable for testing.
8.1.1.4.2Alternative procedures, subject to approval of the Administrator, e.g., installing straightening vanes to eliminate the cyclonic flow, must be implemented prior to conducting the testing.
8.1.1.5Stack Gas Moisture Measurements. Not required. Measuring the moisture content is optional when a mass emission rate is to be calculated.
8.1.1.5.1The tester may elect to either measure the actual stack gas moisture during the sampling run or utilize a nominal moisture value of 2 percent.
8.1.1.5.2For additional information on determining sampling train moisture, please refer to Method 4 (40 CFR part 60, appendix A).
8.1.1.6Stack Temperature Measurements. If a mass emission rate is to be calculated, a temperature sensor must be placed either near the center of the stack, or attached to the pitot tube as described in Section 8.3 of Method 2. Stack temperature measurements, shall be recorded before and after each test, and an average stack temperature determined for the testing period.
8.1.1.7Point Sampling Times. Since the sampling rate of the train (0.75 cfm) is maintained constant by the critical orifice, it is necessary to calculate specific sampling times for each traverse point in order to obtain a proportional sample.
8.1.1.7.1If the sampling period (3 runs) is to be completed in a single day, the point sampling times shall be calculated only once.
8.1.1.7.2If the sampling period is to occur over several days, the sampling times must be calculated daily using the initial velocity pressure data recorded for that day. Determine the average of the Δp values obtained during the velocity traverse (Figure 306A-2).
8.1.1.7.3If the stack diameter is less than 12 inches, use 7.5 minutes in place of 5 minutes in the equation and 16 sampling points instead of 24 or 25 points. Calculate the sampling times for each traverse point using the following equation:
Where:
n = Sampling point number.
Δp = Average pressure differential across pitot tube, mm H2O (in. H2O).
ΔPavg = Average of Δp values, mm H2O (in. H2O).
Note:
Convert the decimal fractions for minutes to seconds.
8.1.1.8Pretest Preparation. It is recommended, but not required, that all items which will be in contact with the sample be cleaned prior to performing the testing to avoid possible sample contamination (positive chromium bias). These items include, but are not limited to: Sampling probe, connecting tubing, impingers, and jar containers.
8.1.1.8.1Sample train components should be: (1) Rinsed with hot tap water; (2) washed with hot soapy water; (3) rinsed with tap water; (4) rinsed with reagent water; (5) soaked in a 10 percent (v/v) nitric acid solution for at least four hours; and (6) rinsed throughly with reagent water before use.
8.1.1.8.2At a minimum, the tester should, rinse the probe, connecting tubing, and first and second impingers twice with either 0.1 N sodium hydroxide (NaOH) or 0.1 N sodium bicarbonate (NaHCO3) and discard the rinse solution.
8.1.1.8.3If separate sample shipping containers are to be used, these also should be precleaned using the specified cleaning procedures.
8.1.1.9Preparation of Sampling Train. Assemble the sampling train as shown in Figure 306A-1. Secure the nozzle-liner assembly to the outer sheath to prevent movement when sampling.
8.1.1.9.1Place 250 mL of 0.1 N NaOH or 0.1 N NaHCO3 absorbing solution into the first jar container or impinger. The second jar/impinger is to remain empty. Place 6 to 16 mesh indicating silica gel, or equivalent desiccant into the third jar/impinger until the container is half full (∼ 300 to 400 g).
8.1.1.9.2Place a small cotton ball in the outlet exit tube of the third jar to collect small silica gel particles that may dislodge and impair the pump and/or gas meter.
8.1.1.10Pretest Leak-Check. A pretest leak-check is recommended, but not required. If the tester opts to conduct the pretest leak-check, the following procedures shall be performed: (1) Place the jar/impinger containers into an ice bath and wait 10 minutes for the ice to cool the containers before performing the leak check and/or start sampling; (2) to perform the leak check, seal the nozzle using a piece of clear plastic wrap placed over the end of a finger and switch on the pump; and (3) the train system leak rate should not exceed 0.02 cfm at a vacuum of 380 mm Hg (15 in. Hg) or greater. If the leak rate does exceed the 0.02 cfm requirement, identify and repair the leak area and perform the leak check again.
Note:
Use caution when releasing the vacuum following the leak check. Always allow air to slowly flow through the nozzle end of the train system while the pump is still operating. Switching off the pump with vacuum on the system may result in the silica gel being pulled into the second jar container.
8.1.1.11Leak-Checks During Sample Run. If, during the sampling run, a component (e.g., jar container) exchange becomes necessary, a leak-check shall be conducted immediately before the component exchange is made. The leak-check shall be performed according to the procedure outlined in Section 8.1.1.10 of this method. If the leakage rate is found to be ≤ 0.02 cfm at the maximum operating vacuum, the results are acceptable. If, however, a higher leak rate is obtained, either record the leakage rate and correct the sample volume as shown in Section 12.3 of Method 5 or void the sample and initiate a replacement run. Following the component change, leak-checks are optional, but are recommended as are the pretest leak-checks.
8.1.1.12Post Test Leak Check. Remove the probe assembly and flexible tubing from the first jar/impinger container. Seal the inlet tube of the first container using clear plastic wrap and switch on the pump. The vacuum in the line between the pump and the critical orifice must be ≥15 in. Hg. Record the vacuum gauge measurement along with the leak rate observed on the train system.
8.1.1.12.1If the leak rate does not exceed 0.02 cfm, the results are acceptable and no sample volume correction is necessary.
8.1.1.12.2If, however, a higher leak rate is obtained (>0.02 cfm), the tester shall either record the leakage rate and correct the sample volume as shown in Section 12.3 of Method 5, or void the sampling run and initiate a replacement run.After completing the leak-check, slowly release the vacuum at the first container while the pump is still operating. Afterwards, switch-off the pump.
8.1.2Sample Train Operation.
8.1.2.1Data Recording. Record all pertinent process and sampling data on the data sheet (see Figure 306A-3). Ensure that the process operation is suitable for sample collection.
8.1.2.2Starting the Test. Place the probe/nozzle into the duct at the first sampling point and switch on the pump. Start the sampling using the time interval calculated for the first point. When the first point sampling time has been completed, move to the second point and continue to sample for the time interval calculated for that point; sample each point on the traverse in this manner. Maintain ice around the sample containers during the run.
8.1.2.3Critical Flow. The sample line between the critical orifice and the pump must operate at a vacuum of ≥ 380 mm Hg (≥15 in. Hg) in order for critical flow to be maintained. This vacuum must be monitored and documented using the vacuum gauge located between the critical orifice and the pump.
Note:
Theoretically, critical flow for air occurs when the ratio of the orifice outlet absolute pressure to the orifice inlet absolute pressure is less than a factor of 0.53. This means that the system vacuum should be at least ≥ 356 mm Hg (≥ 14 in. Hg) at sea level and ∼ 305 mm Hg (∼ 12 in. Hg) at higher elevations.
8.1.2.4Completion of Test.
8.1.2.4.1Circular Stacks. Complete the first port traverse and switch off the pump. Testers may opt to perform a leak-check between the port changes to verify the leak rate however, this is not mandatory. Move the sampling train to the next sampling port and repeat the sequence. Be sure to record the final dry gas meter reading after completing the test run. After performing the post test leak check, disconnect the jar/impinger containers from the pump and meter assembly and transport the probe, connecting tubing, and containers to the sample recovery area.
8.1.2.4.2Rectangle Stacks. Complete each port traverse as per the instructions provided in 8.1.2.4.1.
Note:
If an approximate mass emission rate is to be calculated, measure and record the stack velocity pressure and temperature before and after the test run.
8.2Sample Recovery. After the train has been transferred to the sample recovery area, disconnect the tubing that connects the jar/impingers. The tester shall select either the total Cr or Cr 6 sample recovery option. Samples to be analyzed for both total Cr and Cr 6 shall be recovered using the Cr 6 sample option (Section 8.2.2).
Note:
Collect a reagent blank sample for each of the total Cr or the Cr 6 analytical options. If both analyses (Cr and Cr 6) are to be conducted on the samples, collect separate reagent blanks for each analysis.
8.2.1Total Cr Sample Option.
8.2.1.1Shipping Container No. 1. The first jar container may either be used to store and transport the sample, or if GS impingers are used, samples may be stored and shipped in precleaned 250-mL, 500-mL or 1000-mL polyethylene or glass bottles with leak-free, non-metal screw caps.
8.2.1.1.1Unscrew the lid from the first jar/impinger container.
8.2.1.1.2Lift the inner tube assembly almost out of the container, and using the wash bottle containing fresh absorbing solution, rinse the outside of the tube that was immersed in the container solution; rinse the inside of the tube as well, by rinsing twice from the top of the tube down through the inner tube into the container.
8.2.1.2Recover the contents of the second jar/impinger container by removing the lid and pouring any contents into the first shipping container.
8.2.1.2.1Rinse twice, using fresh absorbing solution, the inner walls of the second container including the inside and outside of the inner tube.
8.2.1.2.2Rinse the connecting tubing between the first and second sample containers with absorbing solution and place the rinses into the first container.
8.2.1.3Position the nozzle, probe and connecting plastic tubing in a vertical position so that the tubing forms a “U”.
8.2.1.3.1Using the wash bottle, partially fill the tubing with fresh absorbing solution. Raise and lower the end of the plastic tubing several times to allow the solution to contact the internal surfaces. Do not allow the solution to overflow or part of the sample will be lost. Place the nozzle end of the probe over the mouth of the first container and elevate the plastic tubing so that the solution flows into the sample container.
8.2.1.3.2Repeat the probe/tubing sample recovery procedure but allow the solution to flow out the opposite end of the plastic tubing into the sample container. Repeat the entire sample recovery procedure once again.
8.2.1.4Use approximately 200 to 300 mL of the 0.1 N NaOH or 0.1 N NaHCO3 absorbing solution during the rinsing of the probe nozzle, probe liner, sample containers, and connecting tubing.
8.2.1.5Place a piece of clear plastic wrap over the mouth of the sample jar to seal the shipping container. Use a standard lid and band assembly to seal and secure the sample in the jar.
8.2.1.5.1Label the jar clearly to identify its contents, sample number and date.
8.2.1.5.2Mark the height of the liquid level on the container to identify any losses during shipping and handling.
8.2.1.5.3Prepare a chain-of-custody sheet to accompany the sample to the laboratory.
8.2.2Cr 6 Sample Option.
8.2.2.1Shipping Container No. 1. The first jar container may either be used to store and transport the sample, or if GS impingers are used, samples may be stored and shipped in precleaned 250-mL, 500-mL or 1000-mL polyethylene or glass bottles with leak-free non-metal screw caps.
8.2.2.1.1Unscrew and remove the lid from the first jar container.
8.2.2.1.2Measure and record the pH of the solution in the first container by using a pH indicator strip. The pH of the solution must be ≥8.5 for NaOH and ≥8.0 for NaHCO3. If not, discard the collected sample, increase the concentration of the NaOH or NaHCO3 absorbing solution to 0.5 M and collect another air emission sample.
8.2.2.2 After measuring the pH of the first container, follow sample recovery procedures described in Sections 8.2.1.1 through 8.2.1.5.
Note:
Since particulate matter is not usually present at chromium electroplating and/or chromium anodizing facilities, it is not necessary to filter the Cr 6 samples unless there is observed sediment in the collected solutions. If it is necessary to filter the Cr 6 solutions, please refer to the EPA Method 0061, Determination of Hexavalent Chromium Emissions from Stationary Sources, Section 7.4, Sample Preparation in SW-846 (see Reference 5) for procedure.
8.2.3Silica Gel Container. Observe the color of the indicating silica gel to determine if it has been completely spent and make a notation of its condition/color on the field data sheet. Do not use water or other liquids to remove and transfer the silica gel.
8.2.4Total Cr and/or Cr 6 Reagent Blank.
8.2.4.1Shipping Container No. 2. Place approximately 500 mL of the 0.1 N NaOH or 0.1 N NaHCO3 absorbing solution in a precleaned, labeled sample container and include with the field samples for analysis.
8.3Sample Preservation, Storage, and Transport.
8.3.1Total Cr Option. Samples that are to be analyzed for total Cr need not be refrigerated.
8.3.2Cr 6 Option. Samples that are to be analyzed for Cr 6 must be shipped and stored at 4 °C (∼40 °F).
Note:
Allow Cr 6 samples to return to ambient temperature prior to analysis.
8.4Sample Holding Times.
8.4.1Total Cr Option. Samples that are to be analyzed for total chromium must be analyzed within 60 days of collection.
8.4.2Cr 6 Option. Samples that are to be analyzed for Cr 6 must be analyzed within 14 days of collection.
9.0Quality Control
9.1Same as Method 306, Section 9.0.
10.0Calibration and Standardization
Note:
Tester shall maintain a performance log of all calibration results.
10.1Pitot Tube. The Type S pitot tube assembly shall be calibrated according to the procedures outlined in Section 10.1 of Method 2.
10.2Temperature Sensor. Use the procedure in Section 10.3 of Method 2 to calibrate the in-stack temperature sensor.
10.3Metering System.
10.3.1Sample Train Dry Gas Meter Calibration. Calibrations may be performed as described in Section 16.2 of Method 5 by either the manufacturer, a firm who provides calibration services, or the tester.
10.3.2Dry Gas Meter Calibration Coefficient (Ym). The meter calibration coefficient (Ym) must be determined prior to the initial use of the meter, and following each field test program. If the dry gas meter is new, the manufacturer will have specified the Ym value for the meter. This Ym value can be used as the pretest value for the first test. For subsequent tests, the tester must use the Ym value established during the pretest calibration.
10.3.3Calibration Orifice. The manufacturer may have included a calibration orifice and a summary spreadsheet with the meter that may be used for calibration purposes. The spreadsheet will provide data necessary to determine the calibration for the orifice and meter (standard cubic feet volume, sample time, etc.). These data were produced when the initial Ym value was determined for the meter.
10.3.4Ym Meter Value Verification or Meter Calibration.
10.3.4.1The Ym meter value may be determined by replacing the sampling train critical orifice with the calibration orifice. Replace the critical orifice assembly by installing the calibration orifice in the same location. The inlet side of the calibration orifice is to be left open to the atmosphere and is not to be reconnected to the sample train during the calibration procedure.
10.3.4.2If the vacuum pump is cold, switch on the pump and allow it to operate (become warm) for several minutes prior to starting the calibration. After stopping the pump, record the initial dry gas meter volume and meter temperature.
10.3.4.3Perform the calibration for the number of minutes specified by the manufacturer's data sheet (usually 5 minutes). Stop the pump and record the final dry gas meter volume and temperature. Subtract the start volume from the stop volume to obtain the Vm and average the meter temperatures (tm).
10.3.5Ym Value Calculation. Ym is the calculated value for the dry gas meter. Calculate Ym using the following equation:
Where:
Pbar = Barometric pressure at meter, mm Hg, (in. Hg).
Pstd = Standard absolute pressure,
Metric = 760 mm Hg.
English = 29.92 in. Hg.
tm = Average dry gas meter temperature, °C, (°F).
Tm = Absolute average dry gas meter temperature,
Metric °K = 273 tm (°C).
English °R = 460 tm(°F).
Tstd = Standard absolute temperature,
Metric = 293 °K.
English = 528 °R.
Vm = Volume of gas sample as measured (actual) by dry gas meter, dcm,(dcf).
Vm(std),mfg = Volume of gas sample measured by manufacture's calibrated orifice and dry gas meter, corrected to standard conditions (pressure/temperature) dscm (dscf).
Ym = Dry gas meter calibration factor, (dimensionless).
10.3.6Ym Comparison. Compare the Ym value provided by the manufacturer (Section 10.3.3) or the pretest Ym value to the post test Ym value using the following equation:
10.3.6.1If this ratio is between 0.95 and 1.05, the designated Ym value for the meter is acceptable for use in later calculations.
10.3.6.1.1If the value is outside the specified range, the test series shall either be: 1) voided and the samples discarded; or 2) calculations for the test series shall be conducted using whichever meter coefficient value (i.e., manufacturers's/pretest Ym value or post test Ym value) produces the lowest sample volume.
10.3.6.1.2If the post test dry gas meter Ym value differs by more than 5% as compared to the pretest value, either perform the calibration again to determine acceptability or return the meter to the manufacturer for recalibration.
10.3.6.1.3The calibration may also be conducted as specified in Section 10.3 or Section 16.0 of Method 5 (40 CFR part 60, appendix A), except that it is only necessary to check the calibration at one flow rate of ∼ 0.75 cfm.
10.3.6.1.4The calibration of the dry gas meter must be verified after each field test program using the same procedures.
Note:
The tester may elect to use the Ym post test value for the next pretest Ym value; e.g., Test 1 post test Ym value and Test 2 pretest Ym value would be the same.
10.4Barometer. Calibrate against a mercury barometer that has been corrected for temperature and elevation.
10.5ICP Spectrometer Calibration. Same as Method 306, Section 10.2.
10.6GFAA Spectrometer Calibration. Same as Method 306, Section 10.3.
10.7IC/PCR Calibration. Same as Method 306, Section 10.4.
11.0Analytical Procedures
Note:
The method determines the chromium concentration in µg Cr/mL. It is important that the analyst measure the volume of the field sample prior to analyzing the sample. This will allow for conversion of µg Cr/mL to µg Cr/sample.
11.1Analysis. Refer to Method 306 for sample preparation and analysis procedures.
12.0Data Analysis and Calculations
12.1Calculations. Perform the calculations, retaining one extra decimal point beyond that of the acquired data. When reporting final results, round number of figures consistent with the original data.
12.2Nomenclature.
A = Cross-sectional area of stack, m2 (ft2).
Bws = Water vapor in gas stream, proportion by volume, dimensionless (assume 2 percent moisture = 0.02).
Cp = Pitot tube coefficient; “S” type pitot coefficient usually 0.840, dimensionless.
CS = Concentration of Cr in sample solution, µg Cr/mL.
CCr = Concentration of Cr in stack gas, dry basis, corrected to standard conditions µg/dscm (gr/dscf).
d = Diameter of stack, m (ft).
D = Digestion factor, dimensionless.
ER = Approximate mass emission rate, mg/hr (lb/hr).
F = Dilution factor, dimensionless.
L = Length of a square or rectangular duct, m (ft).
MCr = Total Cr in each sample, µg (gr).
Ms = Molecular weight of wet stack gas, wet basis, g/g-mole, (lb/lb-mole); in a nominal gas stream at 2% moisture the value is 28.62.
Pbar = Barometric pressure at sampling site, mm Hg (in. Hg).
Ps = Absolute stack gas pressure; in this case, usually the same value as the barometric pressure, mm Hg (in. Hg).
Pstd = Standard absolute pressure:
Metric = 760 mm Hg.
English = 29.92 in. Hg.
Qstd = Average stack gas volumetric flow, dry, corrected to standard conditions, dscm/hr (dscf/hr).
tm = Average dry gas meter temperature, °C (°F).
Tm = Absolute average dry gas meter temperature:
Metric °K = 273 tm (°C).
English °R = 460 tm(°F).
ts = Average stack temperature, °C (°F).
Ts = Absolute average stack gas temperature: Metric °K = 273 ts (°C). English °R = 460 ts(°F).
Tstd = Standard absolute temperature: Metric = 293 °K. English = 528 °R.
Vad = Volume of sample aliquot after digestion (mL).
Vaf = Volume of sample aliquot after dilution (mL).
Vbd = Volume of sample aliquot submitted to digestion (mL).
Vbf = Volume of sample aliquot before dilution (mL).
Vm = Volume of gas sample as measured (actual, dry) by dry gas meter, dcm (dcf).
VmL = Volume of impinger contents plus rinses (mL).
Vm(std) = Volume of gas sample measured by the dry gas meter, corrected to standard conditions (temperature/pressure), dscm (dscf).
vs = Stack gas average velocity, calculated by Method 2, Equation 2-9, m/sec (ft/sec).
W = Width of a square or rectangular duct, m (ft).
Ym = Dry gas meter calibration factor, (dimensionless).
Δp = Velocity head measured by the Type S pitot tube, cm H2O (in. H2O).
Δpavg = Average of Δp values, mm H2O (in. H2O).
12.3Dilution Factor. The dilution factor is the ratio of the volume of sample aliquot after dilution to the volume before dilution. The dilution factor is usually calculated by the laboratory. This ratio is derived by the following equation:
12.4Digestion Factor. The digestion factor is the ratio of the volume of sample aliquot after digestion to the volume before digestion. The digestion factor is usually calculated by the laboratory. This ratio is derived by the following equation.
12.5Total Cr in Sample. Calculate MCr, the total µg Cr in each sample, using the following equation:
12.6Dry Gas Volume. Correct the sample volume measured by the dry gas meter to standard conditions (20 °C, 760 mm Hg or 68 °F, 29.92 in. Hg) using the following equation:
Where:
K1 = Metric units—0.3855 °K/mm Hg.
English units—17.64 °R/in. Hg.
12.7Cr Emission Concentration (CCr). Calculate CCr, the Cr concentration in the stack gas, in µg/dscm (µg/dscf) on a dry basis, corrected to standard conditions, using the following equation:
Note:
To convert µg/dscm (µg/dscf) to mg/dscm (mg/dscf), divide by 1000.
12.8Stack Gas Velocity.
12.8.1Kp = Velocity equation constant:
12.8.2Average Stack Gas Velocity.
12.9Cross sectional area of stack.
12.10Average Stack Gas Dry Volumetric Flow Rate.
Note:
The emission rate may be based on a nominal stack moisture content of 2 percent (0.02). To calculate an emission rate, the tester may elect to use either the nominal stack gas moisture value or the actual stack gas moisture collected during the sampling run.
Volumetric Flow Rate Equation:
Where:
3600 = Conversion factor, sec/hr.
Note:
To convert Qstd from dscm/hr (dscf/hr) to dscm/min (dscf/min), divide Qstd by 60.
12.11Mass emission rate, mg/hr (lb/hr):
13.0Method Performance
13.1Range. The recommended working range for all of the three analytical techniques starts at five times the analytical detection limit (see also Method 306, Section 13.2.2). The upper limit of all three techniques can be extended indefinitely by appropriate dilution.
13.2Sensitivity.
13.2.1Analytical Sensitivity. The estimated instrumental detection limits listed are provided as a guide for an instrumental limit. The actual method detection limits are sample and instrument dependent and may vary as the sample matrix varies.
13.2.1.1ICP Analytical Sensitivity. The minimum estimated detection limits for ICP, as reported in Method 6010A and the recently revised Method 6010B of SW-846 (Reference 1), are 7.0 µg Cr/L and 4.7 µg Cr/L, respectively.
13.2.1.2GFAAS Analytical Sensitivity. The minimum estimated detection limit for GFAAS, as reported in Methods 7000A and 7191 of SW-846 (Reference 1), is 1.0 µg Cr/L.
13.2.1.3IC/PCR Analytical Sensitivity. The minimum detection limit for IC/PCR with a preconcentrator, as reported in Methods 0061 and 7199 of SW-846 (Reference 1), is 0.05 µg Cr 6/L.
13.2.2In-stack Sensitivity. The in-stack sensitivity depends upon the analytical detection limit, the volume of stack gas sampled, and the total volume of the impinger absorbing solution plus the rinses. Using the analytical detection limits given in Sections 13.2.1.1, 13.2.1.2, and 13.2.1.3; a stack gas sample volume of 1.7 dscm; and a total liquid sample volume of 500 mL; the corresponding in-stack detection limits are 0.0014 mg Cr/dscm to 0.0021 mg Cr/dscm for ICP, 0.00029 mg Cr/dscm for GFAAS, and 0.000015 mg Cr 36/dscm for IC/PCR with preconcentration.
Note:
It is recommended that the concentration of Cr in the analytical solutions be at least five times the analytical detection limit to optimize sensitivity in the analyses. Using this guideline and the same assumptions for impinger sample volume and stack gas sample volume (500 mL and 1.7 dscm, respectively), the recommended minimum stack concentrations for optimum sensitivity are 0.0068 mg Cr/dscm to 0.0103 mg Cr/dscm for ICP, 0.0015 mg Cr/dscm for GFAAS, and 0.000074 mg Cr 6 dscm for IC/PCR with preconcentration. If required, the in-stack detection limits can be improved by either increasing the sampling time, the stack gas sample volume, reducing the volume of the digested sample for GFAAS, improving the analytical detection limits, or any combination of the three.
13.3Precision.
13.3.1The following precision data have been reported for the three analytical methods. In each case, when the sampling precision is combined with the reported analytical precision, the resulting overall precision may decrease.
13.3.2Bias data is also reported for GFAAS.
13.4ICP Precision.
13.4.1As reported in Method 6010B of SW-846 (Reference 1), in an EPA round-robin Phase 1 study, seven laboratories applied the ICP technique to acid/distilled water matrices that had been spiked with various metal concentrates. For true values of 10, 50, and 150 µg Cr/L; the mean reported values were 10, 50, and 149 µg Cr/L; and the mean percent relative standard deviations were 18, 3.3, and 3.8 percent, respectively.
13.4.2In another multilaboratory study cited in Method 6010B, a mean relative standard of 8.2 percent was reported for an aqueous sample concentration of approximately 3750 µg Cr/L.
13.5GFAAS Precision. As reported in Method 7191 of SW-846 (Reference 1), in a single laboratory (EMSL), using Cincinnati, Ohio tap water spiked at concentrations of 19, 48, and 77 µg Cr/L, the standard deviations were ±0.1, ±0.2, and ±0.8, respectively. Recoveries at these levels were 97 percent, 101 percent, and 102 percent, respectively.
13.6IC/PCR Precision. As reported in Methods 0061 and 7199 of SW-846 (Reference 1), the precision of IC/PCR with sample preconcentration is 5 to 10 percent; the overall precision for sewage sludge incinerators emitting 120 ng/dscm of Cr 6 and 3.5 µg/dscm of total Cr is 25 percent and 9 percent, respectively; and for hazardous waste incinerators emitting 300 ng/dscm of Cr 6 the precision is 20 percent.
14.0Pollution Prevention
14.1The only materials used in this method that could be considered pollutants are the chromium standards used for instrument calibration and acids used in the cleaning of the collection and measurement containers/labware, in the preparation of standards, and in the acid digestion of samples. Both reagents can be stored in the same waste container.
14.2Cleaning solutions containing acids should be prepared in volumes consistent with use to minimize the disposal of excessive volumes of acid.
14.3To the extent possible, the containers/vessels used to collect and prepare samples should be cleaned and reused to minimize the generation of solid waste.
15.0Waste Management
15.1It is the responsibility of the laboratory and the sampling team to comply with all federal, state, and local regulations governing waste management, particularly the discharge regulations, hazardous waste identification rules, and land disposal restrictions; and to protect the air, water, and land by minimizing and controlling all releases from field operations.
15.2For further information on waste management, consult The Waste Management Manual for Laboratory Personnel and Less is Better-Laboratory Chemical Management for Waste Reduction, available from the American Chemical Society's Department of Government Relations and Science Policy, 1155 16th Street NW, Washington, DC 20036.
16.0References
1. F.R. Clay, Memo, Impinger Collection Efficiency—Mason Jars vs. Greenburg-Smith Impingers, Dec. 1989.
2. Segall, R.R., W.G. DeWees, F.R. Clay, and J.W. Brown. Development of Screening Methods for Use in Chromium Emissions Measurement and Regulations Enforcement. In: Proceedings of the 1989 EPA/A&WMA International Symposium-Measurement of Toxic and Related Air Pollutants, A&WMA Publication VIP-13, EPA Report No. 600/9-89-060, p. 785.
3. Clay, F.R., Chromium Sampling Method. In: Proceedings of the 1990 EPA/A&WMA International Symposium-Measurement of Toxic and Related Air Pollutants, A&WMA Publication VIP-17, EPA Report No. 600/9-90-026, p. 576.
4. Clay, F.R., Proposed Sampling Method 306A for the Determination of Hexavalent Chromium Emissions from Electroplating and Anodizing Facilities. In: Proceedings of the 1992 EPA/A&WMA International Symposium-Measurement of Toxic and Related Air Pollutants, A&WMA Publication VIP-25, EPA Report No. 600/R-92/131, p. 209.
5. Test Methods for Evaluating Solid Waste, Physical/Chemical Methods, SW-846, Third Edition as amended by Updates I, II, IIA, IIB, and III. Document No. 955-001-000001. Available from Superintendent of Documents, U.S. Government Printing Office, Washington, DC, November 1986.
17.0Tables, Diagrams, Flowcharts, and Validation Data
Method 306B—Surface Tension Measurement for Tanks Used at Decorative Chromium Electroplating and Chromium Anodizing Facilities
Note:
This method does not include all of the specifications (e.g., equipment and supplies) and procedures (e.g., sampling and analytical) essential to its performance. Some material is incorporated by reference from other methods in 40 CFR part 60, appendix A and in this part. Therefore, to obtain reliable results, persons using this method should have a thorough knowledge of at least Methods 5 and 306.
1.0Scope and Application
1.1Analyte. Not applicable.
1.2Applicability. This method is applicable to all chromium electroplating and chromium anodizing operations, and continuous chromium plating at iron and steel facilities where a wetting agent is used in the tank as the primary mechanism for reducing emissions from the surface of the plating solution.
2.0Summary of Method
2.1During an electroplating or anodizing operation, gas bubbles generated during the process rise to the surface of the liquid and burst. Upon bursting, tiny droplets of chromic acid become entrained in ambient air. The addition of a wetting agent to the tank bath reduces the surface tension of the liquid and diminishes the formation of these droplets.
2.2This method determines the surface tension of the bath using a stalagmometer or a tensiometer to confirm that there is sufficient wetting agent present.
3.0Definitions [Reserved]
4.0Interferences [Reserved]
5.0Safety
5.1Disclaimer. This method may involve hazardous materials, operations, and equipment. This test method may not address all of the safety problems associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to performing this test method.
6.0Equipment and Supplies
6.1Stalagmometer. Any commercially available stalagmometer or equivalent surface tension measuring device may be used to measure the surface tension of the plating or anodizing tank liquid provided the procedures specified in Section 11.1.2 are followed.
6.2Tensiometer. A tensiometer may be used to measure the surface tension of the tank liquid provided the procedures specified in ASTM Method D 1331-89, Standard Test Methods for Surface and Interfacial Tension of Solutions of Surface Active Agents (incorporated by reference—see § 63.14) are followed.
7.0Reagents and Standards [Reserved]
8.0Sample Collection, Sample Recovery, Sample Preservation, Sample Holding Times, Storage, and Transport [Reserved]
9.0Quality Control [Reserved]
10.0Calibration and Standardization [Reserved]
11.0Analytical Procedure
11.1Procedure. The surface tension of the tank bath may be measured using a tensiometer, stalagmometer, or any other equivalent surface tension measuring device for measuring surface tension in dynes per centimeter.
11.1.1If a tensiometer is used, the procedures specified in ASTM Method D 1331-89 must be followed.
11.1.2If a stalagmometer is used, the procedures specified in Sections 11.1.2.1 through 11.1.2.3 must be followed.
11.1.2.1Check the stalagmometer for visual signs of damage. If the stalagmometer appears to be chipped, cracked, or otherwise in disrepair, the instrument shall not be used.
11.1.2.2Using distilled or deionized water and following the procedures provided by the manufacturer, count the number of drops corresponding to the distilled/deionized water liquid volume between the upper and lower etched marks on the stalagmometer. If the number of drops for the distilled/deionized water is not within ±1 drop of the number indicated on the instrument, the stalagmometer must be cleaned, using the procedures specified in Section 11.1.3 of this method, before using the instrument to measure the surface tension of the tank liquid.
11.1.2.2.1If the stalagmometer must be cleaned, as indicated in Section 11.1.2.2, repeat the procedure specified in Section 11.1.2.2 before proceeding.
11.1.2.2.2If, after cleaning and performing the procedure in Section 11.1.2.2, the number of drops indicated for the distilled/deionized water is not within ±1 drop of the number indicated on the instrument, either use the number of drops corresponding to the distilled/deionized water volume as the reference number of drops, or replace the instrument.
11.1.2.3Determine the surface tension of the tank liquid using the procedures specified by the manufacturer of the stalagmometer.
11.1.3Stalagmometer cleaning procedures. The procedures specified in Sections 11.1.3.1 through 11.1.3.10 shall be used for cleaning a stalagmometer, as required by Section 11.1.2.2.
11.1.3.1Set up the stalagmometer on its stand in a fume hood.
11.1.3.2Place a clean 150 (mL) beaker underneath the stalagmometer and fill the beaker with reagent grade concentrated nitric acid.
11.1.3.3Immerse the bottom tip of the stalagmometer (approximately 1 centimeter (0.5 inches)) into the beaker.
11.1.3.4Squeeze the rubber bulb and pinch at the arrow up (1) position to collapse.
11.1.3.5Place the bulb end securely on top end of stalagmometer and carefully draw the nitric acid by pinching the arrow up (1) position until the level is above the top etched line.
11.1.3.6Allow the nitric acid to remain in stalagmometer for 5 minutes, then carefully remove the bulb, allowing the acid to completely drain.
11.1.3.7Fill a clean 150 mL beaker with distilled or deionized water.
11.1.3.8Using the rubber bulb per the instructions in Sections 11.1.3.4 and 11.1.3.5, rinse and drain stalagmometer with deionized or distilled water.
11.1.3.9Fill a clean 150 mL beaker with isopropyl alcohol.
11.1.3.10Again using the rubber bulb per the instructions in Sections 11.1.3.4 and 11.1.3.5, rinse and drain stalagmometer twice with isopropyl alcohol and allow the stalagmometer to dry completely.
11.2Frequency of Measurements.
11.2.1Measurements of the bath surface tension are performed using a progressive system which decreases the frequency of surface tension measurements required when the proper surface tension is maintained.
11.2.1.1Initially, following the compliance date, surface tension measurements must be conducted once every 4 hours of tank operation for the first 40 hours of tank operation.
11.2.1.2Once there are no exceedances during a period of 40 hours of tank operation, measurements may be conducted once every 8 hours of tank operation.
11.2.1.3Once there are no exceedances during a second period of 40 consecutive hours of tank operation, measurements may be conducted once every 40 hours of tank operation on an on-going basis, until an exceedance occurs. The maximum time interval for measurements is once every 40 hours of tank operation.
11.2.2If a measurement of the surface tension of the solution is above the 40 dynes per centimeter limit when measured using a stalagmometer, above 33 dynes per centimeter when measured using a tensiometer, or above an alternate surface tension limit established during the performance test, the time interval shall revert back to the original monitoring schedule of once every 4 hours. A subsequent decrease in frequency would then be allowed according to Section 11.2.1.
12.0Data Analysis and Calculations
12.1Log Book of Surface Tension Measurements and Fume Suppressant Additions.
12.1.1The surface tension of the plating or anodizing tank bath must be measured as specified in Section 11.2.
12.1.2The measurements must be recorded in the log book. In addition to the record of surface tension measurements, the frequency of fume suppressant maintenance additions and the amount of fume suppressant added during each maintenance addition must be recorded in the log book.
12.1.3The log book will be readily available for inspection by regulatory personnel.
12.2Instructions for Apparatus Used in Measuring Surface Tension.
12.2.1Included with the log book must be a copy of the instructions for the apparatus used for measuring the surface tension of the plating or anodizing bath.
12.2.2If a tensiometer is used, a copy of ASTM Method D 1331-89 must be included with the log book.
13.0Method Performance [Reserved]
14.0Pollution Prevention [Reserved]
15.0Waste Management [Reserved]
16.0References [Reserved]
17.0Tables, Diagrams, Flowcharts, and Validation Data [Reserved]
Method 307—Determination of Emissions From Halogenated Solvent Vapor Cleaning Machines Using a Liquid Level Procedure
1. Applicability and Principle
1.1Applicability. This method is applicable to the determination of the halogenated solvent emissions from solvent vapor cleaners in the idling mode.
1.2Principle. The solvent level in the solvent cleaning machine is measured using inclined liquid level indicators. The change in liquid level corresponds directly to the amount of solvent lost from the solvent cleaning machine.
2. Apparatus
Note:
Mention of trade names or specific products does not constitute endorsement by the Environmental Protection Agency.
2.1Inclined Liquid Level Indicator. A schematic of the inclined liquid level indicators used in this method is shown in figure 307-1; two inclined liquid level indicators having 0.05 centimeters divisions or smaller shall be used. The liquid level indicators shall be made of glass, Teflon, or any similar material that will not react with the solvent being used. A 6-inch by 1-inch slope is recommended; however the slope may vary depending on the size and design of the solvent cleaning machine.
Note:
It is important that the inclined liquid level indicators be constructed with ease of reading in mind. The inclined liquid level indicators should also be mounted so that they can be raised or lowered if necessary to suit the solvent cleaning machine size.
2.2Horizontal Indicator. Device to check the inclined liquid level indicators orientation relative to horizontal.
2.3Velocity Meter. Hotwire and vane anemometers, or other devices capable of measuring the flow rates ranging from 0 to 15.2 meters per minute across the solvent cleaning machine.
3. Procedure
3.1Connection of the Inclined Liquid Level Indicator. Connect one of the inclined liquid level indicators to the boiling sump drain and the other inclined liquid level indicator to the immersion sump drain using Teflon tubing and the appropriate fittings. A schematic diagram is shown in figure 307-2.
3.2Positioning of Velocity Meter. Position the velocity meter so that it measures the flow rate of the air passing directly across the solvent cleaning machine.
3.3Level the Inclined Liquid Level Indicators.
3.4Initial Inclined Liquid Level Indicator Readings. Open the sump drainage valves. Allow the solvent cleaning machine to operate long enough for the vapor zone to form and the system to stabilize (check with manufacturer). Record the inclined liquid level indicators readings and the starting time on the data sheet. A sample data sheet is provided in figure 307-3.
Date
Run
Solvent type
Solvent density, g/m 3 (lb/ft 3)
Length of boiling sump (SB), m (ft)
Width of boiling sump (WB), m (ft)
Length of immersion sump (SI), m (ft)
Width of immersion sump (WI), m (ft)
Length of solvent vapor/air interface (SV), m (ft) ______
Width of solvent vapor/air interface (WV), m (ft) ______
Clock time Boiling sump reading Immersion sump reading Flow rate reading
Figure 307-3. Data sheet.
3.5Final Inclined Liquid Level Indicator Readings. At the end of the 16-hour test run, check to make sure the inclined liquid level indicators are level; if not, make the necessary adjustments. Record the final inclined liquid level indicators readings and time.
3.6Determination of Solvent Vapor/Air Interface Area for Each Sump. Determine the area of the solvent/air interface of the individual sumps. Whenever possible, physically measure these dimensions, rather than using factory specifications. A schematic of the dimensions of a solvent cleaning machine is provided in figure 307-4.
4. Calculations
4.1Nomenclature.
AB = area of boiling sump interface, m2 (ft2).
AI = area of immersion sump interface, m2 (ft2).
AV = area of solvent/air interface, m2 (ft2).
E = emission rate, kg/m2-hr (lb/ft2-hr).
K = 100,000 cm . g/m . kg for metric units.
= 12 in./ft for English units.
LBF = final boiling sump inclined liquid level indicators reading, cm (in.).
LBi = initial boiling sump inclined liquid level indicators reading, cm (in.).
LIf = final immersion sump inclined liquid level indicators reading, cm (in.).
LIi = initial immersion sump inclined liquid level indicators reading, cm (in.).
SB = length of the boiling sump, m (ft).
SI = length of the immersion sump, m (ft).
SV = length of the solvent vapor/air interface, m (ft).
WB = width of the boiling sump, m (ft).
WI = width of the immersion sump, m (ft).
WV = width of the solvent vapor/air interface, m (ft).
ρ = density of solvent, g/m3 (lb/ft3).
θ = test time, hr.
4.2Area of Sump Interfaces. Calculate the areas of the boiling and immersion sump interfaces as follows:
AB = SB WBEq. 307-1
AI = SI WIEq. 307-2
4.3Area of Solvent/Air Interface. Calculate the area of the solvent vapor/air interface as follows:
AV = SV WVEq. 307-3
4.4Emission Rate. Calculate the emission rate as follows:
Method 308—Procedure for Determination of Methanol Emission From Stationary Sources
1.0Scope and Application
1.1Analyte. Methanol. Chemical Abstract Service (CAS) No. 67-56-1.
1.2Applicability. This method applies to the measurement of methanol emissions from specified stationary sources.
2.0Summary of Method
A gas sample is extracted from the sampling point in the stack. The methanol is collected in deionized distilled water and adsorbed on silica gel. The sample is returned to the laboratory where the methanol in the water fraction is separated from other organic compounds with a gas chromatograph (GC) and is then measured by a flame ionization detector (FID). The fraction adsorbed on silica gel is extracted with an aqueous solution of n-propanol and is then separated and measured by GC/FID.
3.0Definitions [Reserved]
4.0Interferences [Reserved]
5.0Safety
5.1Disclaimer. This method may involve hazardous materials, operations, and equipment. This test method does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this test method to establish appropriate safety and health practices and to determine the applicability of regulatory limitations before performing this test method.
5.2Methanol Characteristics. Methanol is flammable and a dangerous fire and explosion risk. It is moderately toxic by ingestion and inhalation.
6.0Equipment and Supplies
6.1Sample Collection. The following items are required for sample collection:
6.1.1Sampling Train. The sampling train is shown in Figure 308-1 and component parts are discussed below.
6.1.1.1Probe. Teflon ®, approximately 6-millimeter (mm) (0.24 inch) outside diameter.
6.1.1.2Impinger. A 30-milliliter (ml) midget impinger. The impinger must be connected with leak-free glass connectors. Silicone grease may not be used to lubricate the connectors.
6.1.1.3Adsorbent Tube. Glass tubes packed with the required amount of the specified adsorbent.
6.1.1.4Valve. Needle valve, to regulate sample gas flow rate.
6.1.1.5Pump. Leak-free diaphragm pump, or equivalent, to pull gas through the sampling train. Install a small surge tank between the pump and rate meter to eliminate the pulsation effect of the diaphragm pump on the rotameter.
6.1.1.6Rate Meter. Rotameter, or equivalent, capable of measuring flow rate to within 2 percent of the selected flow rate of up to 1000 milliliter per minute (ml/min). Alternatively, the tester may use a critical orifice to set the flow rate.
6.1.1.7Volume Meter. Dry gas meter (DGM), sufficiently accurate to measure the sample volume to within 2 percent, calibrated at the selected flow rate and conditions actually encountered during sampling, and equipped with a temperature sensor (dial thermometer, or equivalent) capable of measuring temperature accurately to within 3 °C (5.4 °F).
6.1.1.8Barometer. Mercury (Hg), aneroid, or other barometer capable of measuring atmospheric pressure to within 2.5 mm (0.1 inch) Hg. See the NOTE in Method 5 (40 CFR part 60, appendix A), section 6.1.2.
6.1.1.9Vacuum Gauge and Rotameter. At least 760-mm (30-inch) Hg gauge and 0- to 40-ml/min rotameter, to be used for leak-check of the sampling train.
6.2Sample Recovery. The following items are required for sample recovery:
6.2.1Wash Bottles. Polyethylene or glass, 500-ml, two.
6.2.2Sample Vials. Glass, 40-ml, with Teflon ®-lined septa, to store impinger samples (one per sample).
6.2.3Graduated Cylinder. 100-ml size.
6.3Analysis. The following are required for analysis:
6.3.1Gas Chromatograph. GC with an FID, programmable temperature control, and heated liquid injection port.
6.3.2Pump. Capable of pumping 100 ml/min. For flushing sample loop.
6.3.3Flow Meter. To monitor accurately sample loop flow rate of 100 ml/min.
6.3.4Regulators. Two-stage regulators used on gas cylinders for GC and for cylinder standards.
6.3.5Recorder. To record, integrate, and store chromatograms.
6.3.6Syringes. 1.0- and 10-microliter (l) size, calibrated, for injecting samples.
6.3.7Tubing Fittings. Stainless steel, to plumb GC and gas cylinders.
6.3.8Vials. Two 5.0-ml glass vials with screw caps fitted with Teflon ®-lined septa for each sample.
6.3.9Pipettes. Volumetric type, assorted sizes for preparing calibration standards.
6.3.10Volumetric Flasks. Assorted sizes for preparing calibration standards.
6.3.11Vials. Glass 40-ml with Teflon ®-lined septa, to store calibration standards (one per standard).
7.0Reagents and Standards
Note:
Unless otherwise indicated, all reagents must conform to the specifications established by the Committee on Analytical Reagents of the American Chemical Society. Where such specifications are not available, use the best available grade.
7.1Sampling. The following are required for sampling:
7.1.1Water. Deionized distilled to conform to the American Society for Testing and Materials (ASTM) Specification D 1193-77, Type 3. At the option of the analyst, the potassium permanganate (KMnO4) test for oxidizable organic matter may be omitted when high concentrations of organic matter are not expected to be present.
7.1.2Silica Gel. Deactivated chromatographic grade 20/40 mesh silica gel packed in glass adsorbent tubes. The silica gel is packed in two sections. The front section contains 520 milligrams (mg) of silica gel, and the back section contains 260 mg.
7.2Analysis. The following are required for analysis:
7.2.1Water. Same as specified in section 7.1.1.
7.2.2n-Propanol, 3 Percent. Mix 3 ml of n-propanol with 97 ml of water.
7.2.3Methanol Stock Standard. Prepare a methanol stock standard by weighing 1 gram of methanol into a 100-ml volumetric flask. Dilute to 100 ml with water.
7.2.3.1Methanol Working Standard. Prepare a methanol working standard by pipetting 1 ml of the methanol stock standard into a 100-ml volumetric flask. Dilute the solution to 100 ml with water.
7.2.3.2Methanol Standards For Impinger Samples. Prepare a series of methanol standards by pipetting 1, 2, 5, 10, and 25 ml of methanol working standard solution respectively into five 50-ml volumetric flasks. Dilute the solutions to 50 ml with water. These standards will have 2, 4, 10, 20, and 50 µg/ml of methanol, respectively. After preparation, transfer the solutions to 40-ml glass vials capped with Teflon ® septa and store the vials under refrigeration. Discard any excess solution.
7.2.3.3Methanol Standards for Adsorbent Tube Samples. Prepare a series of methanol standards by first pipetting 10 ml of the methanol working standard into a 100-ml volumetric flask and diluting the contents to exactly 100 ml with 3 percent n-propanol solution. This standard will contain 10 µg/ml of methanol. Pipette 5, 15, and 25 ml of this standard, respectively, into four 50-ml volumetric flasks. Dilute each solution to 50 ml with 3 percent n-propanol solution. These standards will have 1, 3, and 5 µg/ml of methanol, respectively. Transfer all four standards into 40-ml glass vials capped with Teflon ®-lined septa and store under refrigeration. Discard any excess solution.
7.2.4GC Column. Capillary column, 30 meters (100 feet) long with an inside diameter (ID) of 0.53 mm (0.02 inch), coated with DB 624 to a film thickness of 3.0 micrometers, (µm) or an equivalent column. Alternatively, a 30-meter capillary column coated with polyethylene glycol to a film thickness of 1 µm such as AT-WAX or its equivalent.
7.2.5Helium. Ultra high purity.
7.2.6Hydrogen. Zero grade.
7.2.7Oxygen. Zero grade.
8.0Procedure
8.1Sampling. The following items are required for sampling:
8.1.1Preparation of Collection Train. Measure 20 ml of water into the midget impinger. The adsorbent tube must contain 520 mg of silica gel in the front section and 260 mg of silica gel in the backup section. Assemble the train as shown in Figure 308-1. An optional, second impinger that is left empty may be placed in front of the water-containing impinger to act as a condensate trap. Place crushed ice and water around the impinger.
8.1.2Leak Check. A leak check prior to the sampling run is optional; however, a leak check after the sampling run is mandatory. The leak-check procedure is as follows:
Temporarily attach a suitable (e.g., 0-to 40-ml/min) rotameter to the outlet of the DGM, and place a vacuum gauge at or near the probe inlet. Plug the probe inlet, pull a vacuum of at least 250 mm (10 inch) Hg, and note the flow rate as indicated by the rotameter. A leakage rate not in excess of 2 percent of the average sampling rate is acceptable.
Note:
Carefully release the probe inlet plug before turning off the pump.
8.1.3Sample Collection. Record the initial DGM reading and barometric pressure. To begin sampling, position the tip of the Teflon ® tubing at the sampling point, connect the tubing to the impinger, and start the pump. Adjust the sample flow to a constant rate between 200 and 1000 ml/min as indicated by the rotameter. Maintain this constant rate (±10 percent) during the entire sampling run. Take readings (DGM, temperatures at DGM and at impinger outlet, and rate meter) at least every 5 minutes. Add more ice during the run to keep the temperature of the gases leaving the last impinger at 20 °C (68 °F) or less. At the conclusion of each run, turn off the pump, remove the Teflon ® tubing from the stack, and record the final readings. Conduct a leak check as in section 8.1.2. (This leak check is mandatory.) If a leak is found, void the test run or use procedures acceptable to the Administrator to adjust the sample volume for the leakage.
8.2Sample Recovery. The following items are required for sample recovery:
8.2.1Impinger. Disconnect the impinger. Pour the contents of the midget impinger into a graduated cylinder. Rinse the midget impinger and the connecting tubes with water, and add the rinses to the graduated cylinder. Record the sample volume. Transfer the sample to a glass vial and cap with a Teflon ® septum. Discard any excess sample. Place the samples in an ice chest for shipment to the laboratory.
8.2.2.Adsorbent Tubes. Seal the silica gel adsorbent tubes and place them in an ice chest for shipment to the laboratory.
9.0Quality Control
9.1Miscellaneous Quality Control Measures. The following quality control measures are required:
Section Quality control measure Effect
8.1.2, 8.1.3, 10.1 Sampling equipment leak check and calibration Ensures accurate measurement of sample volume.
10.2 GC calibration Ensures precision of GC analysis.
10.0Calibration and Standardization
10.1Metering System. The following items are required for the metering system:
10.1.1Initial Calibration.
10.1.1.1Before its initial use in the field, first leak-check the metering system (drying tube, needle valve, pump, rotameter, and DGM) as follows: Place a vacuum gauge at the inlet to the drying tube, and pull a vacuum of 250 mm (10 inch) Hg; plug or pinch off the outlet of the flow meter, and then turn off the pump. The vacuum shall remain stable for at least 30 seconds. Carefully release the vacuum gauge before releasing the flow meter end.
10.1.1.2Next, remove the drying tube, and calibrate the metering system (at the sampling flow rate specified by the method) as follows: Connect an appropriately sized wet test meter (e.g., 1 liter per revolution (0.035 cubic feet per revolution)) to the inlet of the drying tube. Make three independent calibrations runs, using at least five revolutions of the DGM per run. Calculate the calibration factor, Y (wet test meter calibration volume divided by the DGM volume, both volumes adjusted to the same reference temperature and pressure), for each run, and average the results. If any Y-value deviates by more than 2 percent from the average, the metering system is unacceptable for use. Otherwise, use the average as the calibration factor for subsequent test runs.
10.1.2Posttest Calibration Check. After each field test series, conduct a calibration check as in section 10.1.1 above, except for the following variations: (a) The leak check is not to be conducted, (b) three, or more revolutions of the DGM may be used, and (c) only two independent runs need be made. If the calibration factor does not deviate by more than 5 percent from the initial calibration factor (determined in section 10.1.1), then the DGM volumes obtained during the test series are acceptable. If the calibration factor deviates by more than 5 percent, recalibrate the metering system as in section 10.1.1, and for the calculations, use the calibration factor (initial or recalibration) that yields the lower gas volume for each test run.
10.1.3Temperature Sensors. Calibrate against mercury-in-glass thermometers.
10.1.4Rotameter. The rotameter need not be calibrated, but should be cleaned and maintained according to the manufacturer's instruction.
10.1.5Barometer. Calibrate against a mercury barometer.
10.2Gas Chromatograph. The following procedures are required for the gas chromatograph:
10.2.1Initial Calibration. Inject 1 µl of each of the standards prepared in sections 7.2.3.3 and 7.2.3.4 into the GC and record the response. Repeat the injections for each standard until two successive injections agree within 5 percent. Using the mean response for each calibration standard, prepare a linear least squares equation relating the response to the mass of methanol in the sample. Perform the calibration before analyzing each set of samples.
10.2.2Continuing Calibration. At the beginning of each day, analyze the mid level calibration standard as described in section 10.5.1. The response from the daily analysis must agree with the response from the initial calibration within 10 percent. If it does not, the initial calibration must be repeated.
11.0Analytical Procedure
11.1Gas Chromatograph Operating Conditions. The following operating conditions are required for the GC:
11.1.1Injector. Configured for capillary column, splitless, 200 °C (392 °F).
11.1.2Carrier. Helium at 10 ml/min.
11.1.3Oven. Initially at 45 °C for 3 minutes; then raise by 10 °C to 70 °C; then raise by 70 °C/min to 200 °C.
11.2Impinger Sample. Inject 1 µl of the stored sample into the GC. Repeat the injection and average the results. If the sample response is above that of the highest calibration standard, either dilute the sample until it is in the measurement range of the calibration line or prepare additional calibration standards. If the sample response is below that of the lowest calibration standard, prepare additional calibration standards. If additional calibration standards are prepared, there shall be at least two that bracket the response of the sample. These standards should produce approximately 50 percent and 150 percent of the response of the sample.
11.3Silica Gel Adsorbent Sample. The following items are required for the silica gel adsorbent samples:
11.3.1Preparation of Samples. Extract the front and backup sections of the adsorbent tube separately. With a file, score the glass adsorbent tube in front of the first section of silica gel. Break the tube open. Remove and discard the glass wool. Transfer the first section of the silica gel to a 5-ml glass vial and stopper the vial. Remove the spacer between the first and second section of the adsorbent tube and discard it. Transfer the second section of silica gel to a separate 5-ml glass vial and stopper the vial.
11.3.2Desorption of Samples. Add 3 ml of the 10 percent n-propanol solution to each of the stoppered vials and shake or vibrate the vials for 30 minutes.
11.3.3Inject a 1-µl aliquot of the diluted sample from each vial into the GC. Repeat the injection and average the results. If the sample response is above that of the highest calibration standard, either dilute the sample until it is in the measurement range of the calibration line or prepare additional calibration standards. If the sample response is below that of the lowest calibration standard, prepare additional calibration standards. If additional calibration standards are prepared, there shall be at least two that bracket the response of the sample. These standards should produce approximately 50 percent and 150 percent of the response of the sample.
12.0Data Analysis and Calculations
12.1Nomenclature.
Caf=Concentration of methanol in the front of the adsorbent tube, µg/ml.
Cab=Concentration of methanol in the back of the adsorbent tube, µg/ml.
Ci=Concentration of methanol in the impinger portion of the sample train, µg/ml.
E=Mass emission rate of methanol, µg/hr (lb/hr).
Mtot=Total mass of methanol collected in the sample train, µg.
Pbar=Barometric pressure at the exit orifice of the DGM, mm Hg (in. Hg).
Pstd=Standard absolute pressure, 760 mm Hg (29.92 in. Hg).
Qstd=Dry volumetric stack gas flow rate corrected to standard conditions, dscm/hr (dscf/hr).
Tm=Average DGM absolute temperature, degrees K (°R).
Tstd=Standard absolute temperature, 293 degrees K (528 °R).
Vaf=Volume of front half adsorbent sample, ml.
Vab=Volume of back half adsorbent sample, ml.
Vi=Volume of impinger sample, ml.
Vm=Dry gas volume as measured by the DGM, dry cubic meters (dcm), dry cubic feet (dcf).
Vm(std)=Dry gas volume measured by the DGM, corrected to standard conditions, dry standard cubic meters (dscm), dry standard cubic feet (dscf).
12.2Mass of Methanol. Calculate the total mass of methanol collected in the sampling train using Equation 308-1.
12.3Dry Sample Gas Volume, Corrected to Standard Conditions. Calculate the volume of gas sampled at standard conditions using Equation 308-2.
12.4Mass Emission Rate of Methanol. Calculate the mass emission rate of methanol using Equation 308-3.
13.0Method Performance [Reserved]
14.0Pollution Prevention [Reserved]
15.0Waste Management [Reserved]
16.0Bibliography
1. Rom, J.J. “Maintenance, Calibration, and Operation of Isokinetic Source Sampling Equipment.” Office of Air Programs, Environmental Protection Agency. Research Triangle Park, NC. APTD-0576 March 1972.
2. Annual Book of ASTM Standards. Part 31; Water, Atmospheric Analysis. American Society for Testing and Materials. Philadelphia, PA. 1974. pp. 40-42.
3. Westlin, P.R. and R.T. Shigehara. “Procedure for Calibrating and Using Dry Gas Volume Meters as Calibration Standards.” Source Evaluation Society Newsletter. 3(1) :17-30. February 1978.
4. Yu, K.K. “Evaluation of Moisture Effect on Dry Gas Meter Calibration.” Source Evaluation Society Newsletter. 5(1) :24-28. February 1980.
5. NIOSH Manual of Analytical Methods, Volume 2. U.S. Department of Health and Human Services National Institute for Occupational Safety and Health. Center for Disease Control. 4676 Columbia Parkway, Cincinnati, OH 45226. (available from the Superintendent of Documents, Government Printing Office, Washington, DC 20402.)
6. Pinkerton, J.E. “Method for Measuring Methanol in Pulp Mill Vent Gases.” National Council of the Pulp and Paper Industry for Air and Stream Improvement, Inc., New York, NY.
17.0Tables, Diagrams, Flowcharts, and Validation Data [Reserved]
Method 310A—Determination of Residual Hexane Through Gas Chromatography
1.0Scope and Application
1.1This method is used to analyze any crumb rubber or water samples for residual hexane content.
1.2The sample is heated in a sealed bottle with an internal standard and the vapor is analyzed by gas chromatography.
2.0Summary of Method
2.1This method, utilizing a capillary column gas chromatograph with a flame ionization detector, determines the concentration of residual hexane in rubber crumb samples.
3.0Definitions
3.1The definitions are included in the text as needed.
4.0Interferences
4.1There are no known interferences.
5.0Safety
5.1It is the responsibility of the user of this procedure to establish safety and health practices applicable to their specific operation.
6.0Equipment and Supplies
6.1Gas Chromatograph with a flame ionization detector and data handling station equipped with a capillary column 30 meters long.
6.2Chromatograph conditions for Sigma 1:
6.2.1Helium pressure: 50# inlet A, 14# aux
6.2.2Carrier flow: 25 cc/min
6.2.3Range switch: 100x
6.2.4DB: 1 capillary column
6.3Chromatograph conditions for Hewlett-Packard GC:
6.3.1Initial temperature: 40 °C
6.3.2Initial time: 8 min
6.3.3Rate: 0
6.3.4Range: 2
6.3.5DB: 1705 capillary column
6.4Septum bottles and stoppers
6.5Gas Syringe—0.5 cc
7.0Reagents and Standards
7.1Chloroform, 99.9 %, A.S.C. HPLC grade
8.0Sample Collection, Preservation, and Storage
8.1A representative sample should be caught in a clean 8 oz. container with a secure lid.
8.2The container should be labeled with sample identification, date and time.
9.0Quality Control
9.1The instrument is calibrated by injecting calibration solution (Section 10.2 of this method) five times.
9.2The retention time for components of interest and relative response of monomer to the internal standard is determined.
9.3Recovery efficiency must be determined once for each sample type and whenever modifications are made to the method.
9.3.1Determine the percent hexane in three separate dried rubber crumb samples.
9.3.2Weigh a portion of each crumb sample into separate sample bottles and add a known amount of hexane (10 microliters) by microliter syringe and 20 microliters of internal standard. Analyze each by the described procedure and calculate the percent recovery of the known added hexane.
9.3.3Repeat the previous step using twice the hexane level (20 microliters), analyze and calculate the percent recovery of the known added hexane.
9.3.4Set up two additional sets of samples using 10 microliters and 20 microliters of hexane as before, but add an amount of water equal to the dry crumb used. Analyze and calculate percent recovery to show the effect of free water on the results obtained.
9.3.5A value of R between 0.70 and 1.30 is acceptable.
9.3.6R shall be used to correct all reported results for each compound by dividing the measured results of each compound by the R for that compound for the same sample type.
10.0Calibration and Instrument Settings
10.1Calibrate the chromatograph using a standard made by injecting 10 µl of fresh hexane and 20 µl of chloroform into a sealed septum bottle. This standard will be 0.6 wt.% total hexane based on 1 gram of dry rubber.
10.2Analyze the hexane used and calculate the percentage of each hexane isomer (2-methylpentane, 3-methylpentane, n-hexane, and methylcyclo-pentane). Enter these percentages into the method calibration table.
10.3Heat the standard bottle for 30 minutes in a 105 °C oven.
10.4Inject about 0.25 cc of vapor into the gas chromatograph and after the analysis is finished, calibrate according to the procedures described by the instrument manufacturer.
11.0Procedure
11.1Using a cold mill set at a wide roller gap (125-150 mm), mill about 250 grams of crumb two times to homogenize the sample.
11.2Weigh about 2 grams of wet crumb into a septum bottle and cap with a septum ring. Add 20 µl of chloroform with a syringe and place in a 105 °C oven for 45 minutes.
11.3Run the moisture content on a separate portion of the sample and calculate the grams of dry rubber put into the septum bottle.
11.4Set up the data station on the required method and enter the dry rubber weight in the sample weight field.
11.5Inject a 0.25 cc vapor sample into the chromatograph and push the start button.
11.6At the end of the analysis, the data station will print a report listing the concentration of each identified component.
11.7To analyze water samples, pipet 5 ml of sample into the septum bottle, cap and add 20 µl of chloroform. Place in a 105 °C oven for 30 minutes.
11.8Enter 5 grams into the sample weight field.
11.9Inject a 0.25 cc vapor sample into the chromatograph and push the start button.
11.10At the end of the analysis, the data station will print a report listing the concentration of each identified component.
12.0Data Analysis and Calculation
12.1For samples that are prepared as in section 11 of this method, ppm n-hexane is read directly from the computer.
12.2The formulas for calculation of the results are as follows:
ppmhexane=(Ahexane×Rhexane)/(Ais×Ris)
Where:
Ahexane=area of hexane
Rhexane=response of hexane
Ais=area of the internal standard
Ris=response of the internal standard
% hexane in crumb=(ppmhexane/sample amount)100
12.3Correct the results by the value of R (as determined in sections 9.3.4, 9.3.5, and 9.3.6 of this method).
13.0Method Performance
13.1The test has a standard deviation of 0.14 wt% at 0.66 wt% hexane. Spike recovery of 12 samples at two levels of hexane averaged 102.3%. Note: Recovery must be determined for each type of sample. The values given here are meant to be examples of method performance.
14.0Pollution Prevention
14.1Waste generation should be minimized where possible. Sample size should be an amount necessary to adequately run the analysis.
15.0Waste Management
15.1All waste shall be handled in accordance with federal and state environmental regulations.
16.0References and Publications
16.1DSM Copolymer Test Method T-3380.
Method 310B—Determination of Residual Hexane Through Gas Chromatography
1.0Scope and Application
Analyte CAS No. Matrix Method sensitivity (5.5g sample size)
Hexane 110-54-3 Rubber crumb .01 wt%.
Applicable Termonomer Rubber crumb .001 wt%.
1.1Data Quality Objectives:
In the production of ethylene-propylene terpolymer crumb rubber, the polymer is recovered from solution by flashing off the solvent with steam and hot water. The resulting water-crumb slurry is then pumped to the finishing units. Certain amounts of solvent (hexane being the most commonly used solvent) and diene monomer remain in the crumb. The analyst uses the following procedure to determine those amounts.
2.0Summary of Method
2.1The crumb rubber sample is dissolved in toluene to which heptane has been added as an internal standard. Acetone is then added to this solution to precipitate the crumb, and the supernatant is analyzed for hexane and diene by a gas chromatograph equipped with a flame ionization detector (FID).
3.0Definitions
3.1Included in text as needed.
4.0Interferences
4.1None known.
4.2Benzene, introduced as a contaminant in the toluene solvent, elutes between methyl cyclopentane and cyclohexane. However, the benzene peak is completely resolved.
4.32,2-dimethyl pentane, a minor component of the hexane used in our process, elutes just prior to methyl cyclopentane. It is included as “hexane” in the analysis whether it is integrated separately or included in the methyl cyclopentane peak.
5.0Safety
5.1This procedure does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this procedure to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
5.2Chemicals used in this analysis are flammable and hazardous (see specific toxicity information below). Avoid contact with sources of ignition during sample prep. All handling should be done beneath a hood. Playtex or nitrile gloves recommended.
5.3Hexane is toxic by ingestion and inhalation. Vapor inhalation causes irritation of nasal and respiratory passages, headache, dizziness, nausea, central nervous system depression. Chronic overexposure can cause severe nerve damage. May cause irritation on contact with skin or eyes. May cause damage to kidneys.
5.4Termonomer may be harmful by inhalation, ingestion, or skin absorption. Vapor or mist is irritating to the eyes, mucous membranes, and upper respiratory tract. Causes skin irritation.
5.5Toluene is harmful or fatal if swallowed. Vapor harmful if inhaled. Symptoms: headache, dizziness, hallucinations, distorted perceptions, changes in motor activity, nausea, diarrhea, respiratory irritation, central nervous system depression, unconsciousness, liver, kidney and lung damage. Contact can cause severe eye irritation. May cause skin irritation. Causes irritation of eyes, nose, and throat.
5.6Acetone, at high concentrations or prolonged overexposure, may cause headache, dizziness, irritation of eyes and respiratory tract, loss of strength, and narcosis. Eye contact causes severe irritation; skin contact may cause mild irritation. Concentrations of 20,000 ppm are immediately dangerous to life and health.
5.7Heptane is harmful if inhaled or swallowed. May be harmful if absorbed through the skin. Vapor or mist is irritating to the eyes, mucous membranes, and upper respiratory tract. Prolonged or repeated exposure to skin causes defatting and dermatitis.
5.8The steam oven used to dry the polymer in this procedure is set at 110 °C. Wear leather gloves when removing bottles from the oven.
6.0Equipment and Supplies
6.14000-ml volumetric flask
6.2100-ml volumetric pipette
6.31000-ml volumetric flask
6.48-oz. French Square sample bottles with plastic-lined caps
6.5Top-loading balance
6.6Laboratory shaker
6.7Laboratory oven set at 110 °C (steam oven)
6.8Gas chromatograph, Hewlett-Packard 5890A, or equivalent, interfaced with HP 7673A (or equivalent) autosampler (equipped with nanoliter adapter and robotic arm), and HP 3396 series II or 3392A (or equivalent) integrator/controller.
6.9GC column, capillary type, 50m × 0.53mm, methyl silicone, 5 micron film thickness, Quadrex, or equivalent.
6.10Computerized data acquisition system, such as CIS/CALS
6.11Crimp-top sample vials and HP p/n 5181-1211 crimp caps, or screw-top autosampler vials and screw tops.
6.12Glass syringes, 5-ml, with “Luer-lock” fitting
6.13Filters, PTFE, .45 µm pore size, Gelman Acrodisc or equivalent, to fit on Luer-lock syringes (in 6.12, above).
7.0Reagents and Standards
7.1Reagent toluene, EM Science Omnisolv (or equivalent)
Purity Check: Prior to using any bottle of reagent toluene, analyze it according to section 11.2 of this method. Use the bottle only if hexane, heptane, and termonomer peak areas are less than 15 each (note that an area of 15 is equivalent to less than 0.01 wt% in a 10g sample).
7.2Reagent acetone, EM Science Omnisolv HR-GC (or equivalent)
Purity Check: Prior to using any bottle of reagent acetone, analyze it according to section 11.2 of this method. Use the bottle only if hexane, heptane, and termonomer peak areas are less than 15 each.
7.3Reagent heptane, Aldrich Chemical Gold Label, Cat #15,487-3 (or equivalent)
Purity Check: Prior to using any bottle of reagent heptane, analyze it according to section 11.2 of this method. Use the bottle only if hexane and termonomer peak areas are less than 5 each.
7.4Internal standard solution—used as a concentrate for preparation of the more dilute Polymer Dissolving Solution. It contains 12.00g heptane/100ml of solution which is 120.0g per liter.
Preparation of internal standard solution (polymer dissolving stock solution):
Action Notes
7.4.1Tare a clean, dry 1-liter volumetric flask on the balance. Record the weight to three places If the 1-liter volumetric flask is too tall to fit in the balance case, you can shield the flask from drafts by inverting a paint bucket with a hole cut in the bottom over the balance cover. Allow the neck of the flask to project through the hole in the bucket.
7.4.2Weigh 120.00 g of n-heptane into the flask. Record the total weight of the flask and heptane as well as the weight of heptane added Use 99 % n-heptane from Aldrich or Janssen Chimica.
7.4.3Fill the flask close to the mark with toluene, about 1 to 2″ below the mark Use EM Science Omnisolve toluene, Grade TX0737-1, or equivalent.
7.4.4Shake the flask vigorously to mix the contents Allow any bubbles to clear before proceeding to the next step.
7.4.5Top off the flask to the mark with toluene. Shake vigorously, as in section 7.4.4 of this method, to mix well
7.4.6Weigh the flask containing the solution on the three place balance record the weight
7.4.7 Transfer the contents of the flask to a 1 qt Boston round bottle Discard any excess solution
7.4.8Label the bottle with the identity of the contents, the weights of heptane and toluene used, the date of preparation and the preparer's name Be sure to include the words “Hexane in Crumb Polymer Dissolving Stock Solution” on the label.
7.4.9Refrigerate the completed blend for the use of the routine Technicians
7.5Polymer Dissolving Solution (“PDS”)—Heptane (as internal standard) in toluene. This solution contains 0.3g of heptane internal standard per 100 ml of solution.
7.5.1Preparation of Polymer Dissolving Solution. Fill a 4,000-ml volumetric flask about 3/4 full with toluene.
7.5.2Add 100 ml of the internal standard solution (section 7.4 of this method) to the flask using the 100ml pipette.
7.5.3Fill the flask to the mark with toluene. Discard any excess.
7.5.4Add a large magnetic stirring bar to the flask and mix by stirring.
7.5.5Transfer the polymer solvent solution to the one-gallon labeled container with 50ml volumetric dispenser attached.
7.5.6Purity Check: Analyze according to section 11.2. NOTE: You must “precipitate” the sample with an equal part of acetone (thus duplicating actual test conditions—see section 11.1 of this method, sample prep) before analyzing. Analyze the reagent 3 times to quantify the C6 and termonomer interferences. Inspect the results to ensure good agreement among the three runs (within 10%).
7.5.7Tag the bottle with the following information:
POLYMER DISSOLVING SOLUTION FOR C6 IN CRUMB ANALYSIS
PREPARER'S NAME
DATE
CALS FILE ID'S OF THE THREE ANALYSES FOR PURITY (from section 7.5.6 of this method)
7.6Quality Control Solution: the quality control solution is prepared by adding specific amounts of mixed hexanes (barge hexane), n-nonane and termonomer to some polymer dissolving solution. Nonane elutes in the same approximate time region as termonomer and is used to quantify in that region because it has a longer shelf life. Termonomer, having a high tendency to polymerize, is used in the QC solution only to ensure that both termonomer isomers elute at the proper time.
First, a concentrated stock solution is prepared; the final QC solution can then be prepared by diluting the stock solution.
7.6.1In preparation of stock solution, fill a 1-liter volumetric flask partially with polymer dissolving solution (PDS)—see section 7.5 of this method. Add 20.0 ml barge hexane, 5.0 ml n-nonane, and 3 ml termonomer. Finish filling the volumetric to the mark with PDS.
7.6.2In preparation of quality control solution, dilute the quality control stock solution (above) precisely 1:10 with PDS, i.e. 10 ml of stock solution made up to 100 ml (volumetric flask) with PDS. Pour the solution into a 4 oz. Boston round bottle and store in the refrigerator.
8.0Sample Collection, Preservation and Storage
8.1Line up facility to catch crumb samples. The facility is a special facility where the sample is drawn.
8.1.1Ensure that the cock valve beneath facility is closed.
8.1.2Line up the system from the slurry line cock valve to the cock valve at the nozzle on the stripper.
8.1.3Allow the system to flush through facility for a period of 30 seconds.
8.2Catch a slurry crumb sample.
8.2.1Simultaneously close the cock valves upstream and downstream of facility.
8.2.2Close the cock valve beneath the slurry line in service.
8.2.3Line up the cooling tower water through the sample bomb water jacket to the sewer for a minimum of 30 minutes.
8.2.4Place the sample catching basket beneath facility and open the cock valve underneath the bomb to retrieve the rubber crumb.
8.2.5If no rubber falls by gravity into the basket, line up nitrogen to the bleeder upstream of the sample bomb and force the rubber into the basket.
8.2.6Close the cock valve underneath the sample bomb.
8.3Fill a plastic “Whirl-pak” sample bag with slurry crumb and send it to the lab immediately.
8.4Once the sample reaches the lab, it should be prepped as soon as possible to avoid hexane loss through evaporation. Samples which have lain untouched for more than 30 minutes should be discarded.
9.0Quality Control
Quality control is monitored via a computer program that tracks analyses of a prepared QC sample (from section 7.6.2 of this method). The QC sample result is entered daily into the program, which plots the result as a data point on a statistical chart. If the data point does not satisfy the “in-control” criteria (as defined by the lab quality facilitator), an “out-of-control” flag appears, mandating corrective action.
In addition, the area of the n-heptane peak is monitored so that any errors in making up the polymer dissolving solution will be caught and corrected. Refer to section 12.4 of this method.
9.1Fill an autosampler vial with the quality control solution (from section 7.6.2 of this method) and analyze on the GC as normal (per section 11 of this method).
9.2Add the concentrations of the 5 hexane isomers as they appear on the CALS printout. Also include the 2,2-dimethyl-pentane peak just ahead of the methyl cyclopentane (the fourth major isomer) peak in the event that the peak integration split this peak out. Do not include the benzene peak in the sum. Note the nonane concentration. Record both results (total hexane and nonane) in the QC computer program. If out of control, and GC appears to be functioning within normal parameters, reanalyze a fresh control sample. If the fresh QC is not in control, check stock solution for contaminants or make up a new QC sample with the toluene currently in use. If instrument remains out-of-control, more thorough GC troubleshooting may be needed.
Also, verify that the instrument has detected both isomers of termonomer (quantification not necessary—see section 7.0 of this method).
9.3Recovery efficiency must be determined for high ethylene concentration, low ethylene concentration, E-P terpolymer, or oil extended samples and whenever modifications are made to the method. Recovery shall be between 70 and 130 percent. All test results must be corrected by the recovery efficiency value (R).
9.3.1Approximately 10 grams of wet EPDM crumb (equivalent to about 5 grams of dry rubber) shall be added to six sample bottles containing 100 ml of hexane in crumb polymer dissolving solution (toluene containing 0.3 gram n-heptane/100 ml solution). The polymer shall be dissolved by agitating the bottles on a shaker for 4 hours. The polymer shall be precipitated using 100 ml acetone.
9.3.2The supernatant liquid shall be decanted from the polymer. Care shall be taken to remove as much of the liquid phase from the sample as possible to minimize the effect of retained liquid phase upon the next cycle of the analysis. The supernatant liquid shall be analyzed by gas chromatography using an internal standard quantitation method with heptane as the internal standard.
9.3.3The precipitated polymer from the steps described above shall be redissolved using toluene as the solvent. No heptane shall be added to the sample in the second dissolving step. The toluene solvent and acetone precipitant shall be determined to be free of interfering compounds.
9.3.4The rubber which was dissolved in the toluene shall be precipitated with acetone as before, and the supernatant liquid decanted from the precipitated polymer. The liquid shall be analyzed by gas chromatography and the rubber phase dried in a steam-oven to determine the final polymer weight.
9.3.5The ratios of the areas of the hexane peaks and of the heptane internal standard peak shall be calculated for each of the six samples in the two analysis cycles outlined above. The area ratios of the total hexane to heptane (R1) shall be determined for the two analysis cycles of the sample set. The ratio of the values of R1 from the second analysis cycle to the first cycle shall be determined to give a second ratio (R2).
10.0Calibration and Standardization
The procedure for preparing a Quality Control sample with the internal standard in it is outlined in section 7.6 of this method.
10.1The relative FID response factors for n-heptane, the internal standard, versus the various hexane isomers and termonomer are relatively constant and should seldom need to be altered. However Baseline construction is a most critical factor in the production of good data. For this reason, close attention should be paid to peak integration. Procedures for handling peak integration will depend upon the data system used.
10.2If recalibration of the analysis is needed, make up a calibration blend of the internal standard and the analytes as detailed below and analyze it using the analytical method used for the samples.
10.2.1Weigh 5 g heptane into a tared scintillation vial to five places.
10.2.2Add 0.2 ml termonomer to the vial and reweigh.
10.2.3Add 0.5 ml hexane to the vial and reweigh.
10.2.4Cap, and shake vigorously to mix.
10.2.5Calculate the weights of termonomer and of hexane added and divide their weights by the weight of the n-heptane added. The result is the known of given value for the calibration.
10.2.6Add 0.4 ml of this mixture to a mixture of 100 ml toluene and 100 ml of acetone. Cap and shake vigorously to mix.
10.2.7Analyze the sample.
10.2.8Divide the termonomer area and the total areas of the hexane peaks by the n-heptane area. This result is the “found” value for the calibration.
10.2.9Divide the appropriate “known” value from 10.2.5 by the found value from 10.2.8. The result is the response factor for the analyte in question. Previous work has shown that the standard deviation of the calibration method is about 1% relative.
11.0Procedure
11.1SAMPLE PREPARATION
11.1.1Tare an 8oz sample bottle—Tag attached, cap off; record weight and sample ID on tag in pencil.
11.1.2Place crumb sample in bottle: RLA-3: 10 g (gives a dry wt. of ∼5.5 g).
11.1.3Dispense 100ml of PDS into each bottle. SAMPLE SHOULD BE PLACED INTO SOLUTION ASAP TO AVOID HEXANE LOSS—Using “Dispensette” pipettor. Before dispensing, “purge” the dispensette (25% of its volume) into a waste bottle to eliminate any voids.
11.1.4Tightly cap bottles and load samples into shaker.
11.1.5Insure that “ON-OFF” switch on the shaker itself is “ON.”
11.1.6Locate shaker timer. Insure that toggle switch atop timer control box is in the middle (“off”) position. If display reads “04:00” (4 hours), move toggle switch to the left position. Shaker should begin operating.
11.1.7After shaker stops, add 100 ml acetone to each sample to precipitate polymer. Shake minimum of 5 minutes on shaker—Vistalon sample may not have fully dissolved; nevertheless, for purposes of consistency, 4 hours is the agreed-upon dissolving time.
11.1.8Using a 5-ml glass Luer-lock syringe and Acrodisc filter, filter some of the supernatant liquid into an autosampler vial; crimp the vial and load it into the GC autosampler for analysis (section 11.2 of this method)—The samples are filtered to prevent polymer buildup in the GC. Clean the syringes in toluene.
11.1.9Decant remaining supernatant into a hydrocarbon waste sink, being careful not to discard any of the polymer. Place bottle of precipitate into the steam oven and dry for six hours—Some grades of Vistalon produce very small particles in the precipitate, thus making complete decanting impossible without discarding some polymer. In this case, decant as much as possible and put into the oven as is, allowing the oven to drive off remaining supernatant (this practice is avoided for environmental reasons). WARNING: OVEN IS HOT—110 °C (230 °F).
11.1.10Cool, weigh and record final weight of bottle.
11.2GC ANALYSIS
11.2.1Initiate the CALS computer channel.
11.2.2Enter the correct instrument method into the GC's integrator.
11.2.3Load sample vial(s) into autosampler.
11.2.4Start the integrator.
11.2.5When analysis is complete, plot CALS run to check baseline skim.
12.0 Data Analysis and Calculations
12.1Add the concentrations of the hexane peaks as they appear on the CALS printout. Do not include the benzene peak in the sum.
12.2Subtract any hexane interferences found in the PDS (see section 7.5.6 of this method); record the result.
12.3Note the termonomer concentration on the CALS printout. Subtract any termonomer interference found in the PDS and record this result in a “% termonomer by GC” column in a logbook.
12.4Record the area (from CALS printout) of the heptane internal standard peak in a “C7 area” column in the logbook. This helps track instrument performance over the long term.
12.5After obtaining the final dry weight of polymer used (Section 11.1.10 of this method), record that result in a “dry wt.” column of the logbook (for oil extended polymer, the amount of oil extracted is added to the dry rubber weight).
12.6Divide the by the dry weight to obtain the total PHR hexane in crumb. Similarly, divide the % termonomer by the dry weight to obtain the total PHR termonomer in crumb. Note that PHR is an abbreviation for “parts per hundred”. Record both the hexane and termonomer results in the logbook.
12.7Correct all results by the recovery efficiency value (R).
13.0Method Performance
13.1The method has been shown to provide 100% recovery of the hexane analyte. The method was found to give a 6% relative standard deviation when the same six portions of the same sample were carried through the procedure. Note: These values are examples; each sample type, as specified in Section 9.3, must be tested for sample recovery.
14.0Pollution Prevention
14.1Dispose of all hydrocarbon liquids in the appropriate disposal sink system; never pour hydrocarbons down a water sink.
14.2As discussed in section 11.1.9 of this method, the analyst can minimize venting hydrocarbon vapor to the atmosphere by decanting as much hydrocarbon liquid as possible before oven drying.
15.0Waste Management
15.1The Technician conducting the analysis should follow the proper waste management practices for their laboratory location.
16.0References
16.1Baton Rouge Chemical Plant Analytical Procedure no. BRCP 1302
16.2Material Safety Data Sheets (from chemical vendors) for hexane, ENB, toluene, acetone, and heptane
Method 310C—Determination of Residual N-Hexane in EPDM Rubber Through Gas Chromatography
1.0Scope and Application
1.1This method describes a procedure for the determination of residual hexane in EPDM wet crumb rubber in the 0.01—2% range by solvent extraction of the hexane followed by gas chromatographic analysis where the hexane is detected by flame ionization and quantified via an internal standard.
1.2This method may involve hazardous materials operations and equipment. This method does not purport to address all the safety problems associated with it use, if any. It is the responsibility of the user to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
2.0Summary
2.1Residual hexane contained in wet pieces of EPDM polymer is extracted with MIBK. A known amount of an internal standard (IS) is added to the extract which is subsequently analyzed via gas chromatography where the hexane and IS are separated and detected utilizing a megabore column and flame ionization detection (FID). From the response to the hexane and the IS, the amount of hexane in the EPDM polymer is calculated.
3.0Definitions
3.1Hexane—refers to n-hexane
3.2Heptane—refers to n-heptane
3.3MIBK—methyl isobutyl ketone (4 methyl 2—Pentanone)
4.0Interferences
4.1Material eluting at or near the hexane and/or the IS will cause erroneous results. Prior to extraction, solvent blanks must be analyzed to confirm the absence of interfering peaks.
5.0Safety
5.1Review Material Safety Data Sheets of the chemicals used in this method.
6.0Equipment and Supplies
6.14 oz round glass jar with a wide mouth screw cap lid.
6.2Vacuum oven.
6.350 ml pipettes.
6.4A gas chromatograph with an auto sampler and a 50 meter, 0.53 ID, methyl silicone column with 5 micron phase thickness.
6.5Shaker, large enough to hold 10, 4 oz. jars.
6.61000 and 4000 ml volumetric flasks.
6.7Electronic integrator or equivalent data system.
6.8GC autosampler vials.
6.950 uL syringe.
7.0Reagents and Standards
7.1Reagent grade Methyl-Iso-Butyl-Ketone (MIBK)
7.2n-heptane, 99% purity
7.3n-hexane, 99% purity
8.0Sample Collection
8.1Trap a sample of the EPDM crumb slurry in the sampling apparatus. Allow the crumb slurry to circulate through the sampling apparatus for 5 minutes; then close off the values at the bottom and top of the sampling apparatus, trapping the crumb slurry. Run cooling water through the water jacket for a minimum of 30 minutes. Expel the cooled crumb slurry into a sample catching basket. If the crumb does not fall by gravity, force it out with demineralized water or nitrogen. Send the crumb slurry to the lab for analysis.
9.0Quality Control
9.1The Royalene crumb sample is extracted three times with MIBK containing an internal standard. The hexane from each extraction is added together to obtain a total hexane content. The percent hexane in the first extraction is then calculated and used as the recovery factor for the analysis.
9.2Follow this test method through section 11.4 of the method. After removing the sample of the first extraction to be run on the gas chromatograph, drain off the remainder of the extraction solvent, retaining the crumb sample in the sample jar. Rinse the crumb with demineralized water to remove any MIBK left on the surface of the crumb. Repeat the extraction procedure with fresh MIBK with internal standard two more times.
9.3After the third extraction, proceed to section 11.5 of this method and obtain the percent hexane in each extraction. Use the sample weight obtained in section 12.1 of this method to calculate the percent hexane in each of the extracts.
9.4Add the percent hexane obtained from the three extractions for a total percent hexane in the sample.
9.5Use the following equations to determine the recovery factor (R):
% Recovery of the first extraction=(% hexane in the first extract/total % hexane)×100
Recovery Factor (R)=(% Hexane Recovered in the first extract)/100
10.0Calibration
10.1Preparation of Internal Standard (IS) solution:
Accuracy weigh 30 grams of n-heptane into a 1000 ml volumetric flask. Dilute to the mark with reagent grade MIBK. Label this Solution “A”. Pipette 100 mls. of Solution A into a 4 liter volumetric flask. Fill the flask to the mark with reagent MIBK. Label this Solution “B”. Solution “B” will have a concentration of 0.75 mg/ml of heptane.
10.2Preparation of Hexane Standard Solution (HS):
Using a 50 uL syringe, weigh by difference, 20 mg of n-hexane into a 50 ml volumetric flask containing approximately 40 ml of Solution B. Fill the flask to the mark with Solution B and mix well.
10.3Conditions for GC analysis of standards and samples:
Temperature:
Initial=40 °C
Final=150 °C
Injector=160 °C
Detector=280 °C
Program Rate=5.0 °C/min
Initial Time=5 minutes Final Time=6 minutes
Flow Rate=5.0 ml/min
Sensitivity=detector response must be adjusted to keep the hexane and IS on scale.
10.4Fill an autosampler vial with the HS, analyze it three times and calculate a Hexane Relative Response Factor (RF) as follows:
RF=(AIS × CHS × PHS)/(AHS × CIS × PIS)(1)
Where:
AIS=Area of IS peak (Heptane)
AHS=Area of peak (Hexane Standard)
CHS=Mg of Hexane/50 ml HS
CIS=Mg of Heptane/50 ml IS Solution B
PIS=Purity of the IS n-heptane
PHS=Purity of the HS n-hexane
11.0Procedure
11.1Weight 10 grams of wet crumb into a tared (W1), wide mouth 4 oz. jar.
11.2Pipette 50 ml of Solution B into the jar with the wet crumb rubber.
11.3Screw the cap on tightly and place it on a shaker for 4 hours.
11.4Remove the sample from the shaker and fill an autosampler vial with the MIBK extract.
11.5Analyze the sample two times.
11.6Analyze the HS twice, followed by the samples. Inject the HS twice at the end of each 10 samples or at the end of the run.
12.0Calculations
12.1Drain off the remainder of the MIBK extract from the polymer in the 4 oz. jar. Retain all the polymer in the jar. Place the uncovered jar and polymer in a heated vacuum oven until the polymer is dry. Reweigh the jar and polymer (W2) and calculate the dried sample weight of the polymer as follows:
Dried SW=W2—W1 (2)
12.2Should the polymer be oil extended, pipette 10 ml of the MIBK extract into a tared evaporating dish (W1) and evaporate to dryness on a steam plate.
Reweigh the evaporating dish containing the extracted oil (W2). Calculate the oil content of the polymer as follows:
Gram of oil extracted =5 (W2—W1)(3)
% Hexane in polymer=(As×RF×CIS×PIS)/(AIS×SW)(4)
Where:
As=Area of sample hexane sample peak.
AIS=Area of IS peak in sample.
CIS=Concentration of IS in 50 ml.
PIS=Purity of IS.
SW=Weight of dried rubber after extraction. (For oil extended polymer, the amount of oil extracted is added to the dry rubber weight).
% Corrected Hexane=(% Hexane in Polymer)/R (5)
R=Recovery factor determined in section 9 of this method.
13.0Method Performance
13.1Performance must be determined for each sample type by following the procedures in section 9 of this method.
14.0Waste Generation
14.1Waste generation should be minimized where possible.
15.0Waste Management
15.1All waste shall be handled in accordance with Federal and State environmental regulations.
16.0References [Reserved]
Method 311—Analysis of Hazardous Air Pollutant Compounds in Paints and Coatings by Direct Injection Into a Gas Chromatograph
1. Scope and Application
1.1Applicability. This method is applicable for determination of most compounds designated by the U.S. Environmental Protection Agency as volatile hazardous air pollutants (HAP's) (See Reference 1) that are contained in paints and coatings. Styrene, ethyl acrylate, and methyl methacrylate can be measured by ASTM D 4827-93 or ASTM D 4747-87. Formaldehyde can be measured by ASTM PS 9-94 or ASTM D 1979-91. Toluene diisocyanate can be measured in urethane prepolymers by ASTM D 3432-89. Method 311 applies only to those volatile HAP's which are added to the coating when it is manufactured, not to those which may form as the coating cures (reaction products or cure volatiles). A separate or modified test procedure must be used to measure these reaction products or cure volatiles in order to determine the total volatile HAP emissions from a coating. Cure volatiles are a significant component of the total HAP content of some coatings. The term “coating” used in this method shall be understood to mean paints and coatings.
1.2Principle. The method uses the principle of gas chromatographic separation and quantification using a detector that responds to concentration differences. Because there are many potential analytical systems or sets of operating conditions that may represent useable methods for determining the concentrations of the compounds cited in Section 1.1 in the applicable matrices, all systems that employ this principle, but differ only in details of equipment and operation, may be used as alternative methods, provided that the prescribed quality control, calibration, and method performance requirements are met. Certified product data sheets (CPDS) may also include information relevant to the analysis of the coating sample including, but not limited to, separation column, oven temperature, carrier gas, injection port temperature, extraction solvent, and internal standard.
2. Summary of Method
Whole coating is added to dimethylformamide and a suitable internal standard compound is added. An aliquot of the sample mixture is injected onto a chromatographic column containing a stationary phase that separates the analytes from each other and from other volatile compounds contained in the sample. The concentrations of the analytes are determined by comparing the detector responses for the sample to the responses obtained using known concentrations of the analytes.
3. Definitions [Reserved]
4. Interferences
4.1Coating samples of unknown composition may contain the compound used as the internal standard. Whether or not this is the case may be determined by following the procedures of Section 11 and deleting the addition of the internal standard specified in Section 11.5.3. If necessary, a different internal standard may be used.
4.2The GC column and operating conditions developed for one coating formulation may not ensure adequate resolution of target analytes for other coating formulations. Some formulations may contain nontarget analytes that coelute with target analytes. If there is any doubt about the identification or resolution of any gas chromatograph (GC) peak, it may be necessary to analyze the sample using a different GC column or different GC operating conditions.
4.3Cross-contamination may occur whenever high-level and low-level samples are analyzed sequentially. The order of sample analyses specified in Section 11.7 is designed to minimize this problem.
4.4Cross-contamination may also occur if the devices used to transfer coating during the sample preparation process or for injecting the sample into the GC are not adequately cleaned between uses. All such devices should be cleaned with acetone or other suitable solvent and checked for plugs or cracks before and after each use.
5. Safety
5.1Many solvents used in coatings are hazardous. Precautions should be taken to avoid unnecessary inhalation and skin or eye contact. This method may involve hazardous materials, operations, and equipment. This test method does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this test method to establish appropriate safety and health practices and to determine the applicability of regulatory limitations in regards to the performance of this test method.
5.2Dimethylformamide is harmful if inhaled or absorbed through the skin. The user should obtain relevant health and safety information from the manufacturer. Dimethylformamide should be used only with adequate ventilation. Avoid contact with skin, eyes, and clothing. In case of contact, immediately flush skin or eyes with plenty of water for at least 15 minutes. If eyes are affected, consult a physician. Remove and wash contaminated clothing before reuse.
5.3User's manuals for the gas chromatograph and other related equipment should be consulted for specific precautions to be taken related to their use.
6. Equipment and Supplies
Note:
Certified product data sheets (CPDS) may also include information relevant to the analysis of the coating sample including, but not limited to, separation column, oven temperature, carrier gas, injection port temperature, extraction solvent, and internal standard.
6.1Sample Collection.
6.1.1Sampling Containers. Dual-seal sampling containers, four to eight fluid ounce capacity, should be used to collect the samples. Glass sample bottles or plastic containers with volatile organic compound (VOC) impermeable walls must be used for corrosive substances (e.g., etch primers and certain coating catalysts such as methyl ethyl ketone (MEK) peroxide). Sample containers, caps, and inner seal liners must be inert to the compounds in the sample and must be selected on a case-by-case basis.
6.1.1.1Other routine sampling supplies needed include waterproof marking pens, tubing, scrappers/spatulas, clean rags, paper towels, cooler/ice, long handle tongs, and mixing/stirring paddles.
6.1.2Personal safety equipment needed includes eye protection, respiratory protection, a hard hat, gloves, steel toe shoes, etc.
6.1.3Shipping supplies needed include shipping boxes, packing material, shipping labels, strapping tape, etc.
6.1.4Data recording forms and labels needed include coating data sheets and sample can labels.
Note:
The actual requirements will depend upon the conditions existing at the source sampled.
6.2Laboratory Equipment and Supplies.
6.2.1Gas Chromatograph (GC). Any instrument equipped with a flame ionization detector and capable of being temperature programmed may be used. Optionally, other types of detectors (e.g., a mass spectrometer), and any necessary interfaces, may be used provided that the detector system yields an appropriate and reproducible response to the analytes in the injected sample. Autosampler injection may be used, if available.
6.2.2Recorder. If available, an electronic data station or integrator may be used to record the gas chromatogram and associated data. If a strip chart recorder is used, it must meet the following criteria: A 1 to 10 millivolt (mV) linear response with a full scale response time of 2 seconds or less and a maximum noise level of ±0.03 percent of full scale. Other types of recorders may be used as appropriate to the specific detector installed provided that the recorder has a full scale response time of 2 seconds or less and a maximum noise level of ±0.03 percent of full scale.
6.2.3Column. The column must be constructed of materials that do not react with components of the sample (e.g., fused silica, stainless steel, glass). The column should be of appropriate physical dimensions (e.g., length, internal diameter) and contain sufficient suitable stationary phase to allow separation of the analytes. DB-5, DB-Wax, and FFAP columns are commonly used for paint analysis; however, it is the responsibility of each analyst to select appropriate columns and stationary phases.
6.2.4Tube and Tube Fittings. Supplies to connect the GC and gas cylinders.
6.2.5Pressure Regulators. Devices used to regulate the pressure between gas cylinders and the GC.
6.2.6Flow Meter. A device used to determine the carrier gas flow rate through the GC. Either a digital flow meter or a soap film bubble meter may be used to measure gas flow rates.
6.2.7Septa. Seals on the GC injection port through which liquid or gas samples can be injected using a syringe.
6.2.8Liquid Charging Devices. Devices used to inject samples into the GC such as clean and graduated 1, 5, and 10 microliter (µl) capacity syringes.
6.2.9Vials. Containers that can be sealed with a septum in which samples may be prepared or stored. The recommended size is 25 ml capacity. Mininert ® valves have been found satisfactory and are available from Pierce Chemical Company, Rockford, Illinois.
6.2.10Balance. Device used to determine the weights of standards and samples. An analytical balance capable of accurately weighing to 0.0001 g is required.
7. Reagents and Standards
7.1Purity of Reagents. Reagent grade chemicals shall be used in all tests. Unless otherwise specified, all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available. Other grades may be used provided it is first ascertained that the reagent is of sufficient purity to permit its use without lessening the accuracy of determination.
7.2Carrier Gas. Helium carrier gas shall have a purity of 99.995 percent or higher. High purity nitrogen may also be used. Other carrier gases that are appropriate for the column system and analyte may also be used. Ultra-high purity grade hydrogen gas and zero-grade air shall be used for the flame ionization detector.
7.3Dimethylformamide (DMF). Solvent for all standards and samples. Some other suitable solvent may be used if DMF is not compatible with the sample or coelutes with a target analyte.
Note:
DMF may coelute with ethylbenzene or p-xylene under the conditions described in the note under Section 6.2.3.
7.4Internal Standard Materials. The internal standard material is used in the quantitation of the analytes for this method. It shall be gas chromatography spectrophotometric quality or, if this grade is not available, the highest quality available. Obtain the assay for the internal standard material and maintain at that purity during use. The recommended internal standard material is 1-propanol; however, selection of an appropriate internal standard material for the particular coating and GC conditions used is the responsibility of each analyst.
7.5Reference Standard Materials. The reference standard materials are the chemicals cited in Section 1.1 which are of known identity and purity and which are used to assist in the identification and quantification of the analytes of this method. They shall be the highest quality available. Obtain the assays for the reference standard materials and maintain at those purities during use.
7.6Stock Reference Standards. Stock reference standards are dilutions of the reference standard materials that may be used on a daily basis to prepare calibration standards, calibration check standards, and quality control check standards. Stock reference standards may be prepared from the reference standard materials or purchased as certified solutions.
7.6.1Stock reference standards should be prepared in dimethylformamide for each analyte expected in the coating samples to be analyzed. The concentrations of analytes in the stock reference standards are not specified but must be adequate to prepare the calibration standards required in the method. A stock reference standard may contain more than one analyte provided all analytes are chemically compatible and no analytes coelute. The actual concentrations prepared must be known to within 0.1 percent (e.g., 0.1000 ±0.0001 g/g solution). The following procedure is suggested. Place about 35 ml of dimethylformamide into a tared ground-glass stoppered 50 ml volumetric flask. Weigh the flask to the nearest 0.1 mg. Add 12.5 g of the reference standard material and reweigh the flask. Dilute to volume with dimethylformamide and reweigh. Stopper the flask and mix the contents by inverting the flask several times. Calculate the concentration in grams per gram of solution from the net gain in weights, correcting for the assayed purity of the reference standard material.
Note:
Although a glass-stoppered volumetric flask is convenient, any suitable glass container may be used because stock reference standards are prepared by weight.
7.6.2Transfer the stock reference standard solution into one or more Teflon-sealed screw-cap bottles. Store, with minimal headspace, at −10 °C to 0 °C and protect from light.
7.6.3Prepare fresh stock reference standards every six months, or sooner if analysis results from daily calibration check standards indicate a problem. Fresh stock reference standards for very volatile HAP's may have to be prepared more frequently.
7.7Calibration Standards. Calibration standards are used to determine the response of the detector to known amounts of reference material. Calibration standards must be prepared at a minimum of three concentration levels from the stock reference standards (see Section 7.6). Prepare the calibration standards in dimethylformamide (see Section 7.3). The lowest concentration standard should contain a concentration of analyte equivalent either to a concentration of no more than 0.01% of the analyte in a coating or to a concentration that is lower than the actual concentration of the analyte in the coating, whichever concentration is higher. The highest concentration standard should contain a concentration of analyte equivalent to slightly more than the highest concentration expected for the analyte in a coating. The remaining calibration standard should contain a concentration of analyte roughly at the midpoint of the range defined by the lowest and highest concentration calibration standards. The concentration range of the standards should thus correspond to the expected range of analyte concentrations in the prepared coating samples (see Section 11.5). Each calibration standard should contain each analyte for detection by this method expected in the actual coating samples (e.g., some or all of the compounds listed in Section 1.1 may be included). Each calibration standard should also contain an appropriate amount of internal standard material (response for the internal standard material is within 25 to 75 percent of full scale on the attenuation setting for the particular reference standard concentration level). Calibration Standards should be stored for 1 week only in sealed vials with minimal headspace. If the stock reference standards were prepared as specified in Section 7.6, the calibration standards may be prepared by either weighing each addition of the stock reference standard or by adding known volumes of the stock reference standard and calculating the mass of the standard reference material added. Alternative 1 (Section 7.7.1) specifies the procedure to be followed when the stock reference standard is added by volume. Alternative 2 (Section 7.7.2) specifies the procedure to be followed when the stock reference standard is added by weight.
Note:
To assist with determining the appropriate amount of internal standard to add, as required here and in other sections of this method, the analyst may find it advantageous to prepare a curve showing the area response versus the amount of internal standard injected into the GC.
7.7.1Preparation Alternative 1. Determine the amount of each stock reference standard and dimethylformamide solvent needed to prepare approximately 25 ml of the specific calibration concentration level desired. To a tared 25 ml vial that can be sealed with a crimp-on or Mininert ® valve, add the total amount of dimethylformamide calculated to be needed. As quickly as practical, add the calculated amount of each stock reference standard using new pipets (or pipet tips) for each stock reference standard. Reweigh the vial and seal it. Using the known weights of the standard reference materials per ml in the stock reference standards, the volumes added, and the total weight of all reagents added to the vial, calculate the weight percent of each standard reference material in the calibration standard prepared. Repeat this process for each calibration standard to be prepared.
7.7.2Preparation Alternative 2. Determine the amount of each stock reference standard and dimethylformamide solvent needed to prepare approximately 25 ml of the specific calibration concentration level desired. To a tared 25 ml vial that can be sealed with a crimp-on or Mininert ® valve, add the total amount of dimethylformamide calculated to be needed. As quickly as practical, add the calculated amount of a stock reference standard using a new pipet (or pipet tip) and reweigh the vial. Repeat this process for each stock reference standard to be added. Seal the vial after obtaining the final weight. Using the known weight percents of the standard reference materials in the stock reference standards, the weights of the stock reference standards added, and the total weight of all reagents added to the vial, calculate the weight percent of each standard reference material in the calibration standard prepared. Repeat this process for each calibration standard to be prepared.
8. Sample Collection, Preservation, Transport, and Storage
8.1Copies of material safety data sheets (MSDS's) for each sample should be obtained prior to sampling. The MSDS's contain information on the ingredients, and physical and chemical properties data. The MSDS's also contain recommendations for proper handling or required safety precautions. Certified product data sheets (CPDS) may also include information relevant to the analysis of the coating sample including, but not limited to, separation column, oven temperature, carrier gas, injection port temperature, extraction solvent, and internal standard.
8.2A copy of the blender's worksheet can be requested to obtain data on the exact coating being sampled. A blank coating data sheet form (see Section 18) may also be used. The manufacturer's formulation information from the product data sheet should also be obtained.
8.3Prior to sample collection, thoroughly mix the coating to ensure that a representative, homogeneous sample is obtained. It is preferred that this be accomplished using a coating can shaker or similar device; however, when necessary, this may be accomplished using mechanical agitation or circulation systems.
8.3.1Water-thinned coatings tend to incorporate or entrain air bubbles if stirred too vigorously; mix these types of coatings slowly and only as long as necessary to homogenize.
8.3.2Each component of multicomponent coatings that harden when mixed must be sampled separately. The component mix ratios must be obtained at the facility at the time of sampling and submitted to the analytical laboratory.
8.4Sample Collection. Samples must be collected in a manner that prevents or minimizes loss of volatile components and that does not contaminate the coating reservoir. A suggested procedure is as follows. Select a sample collection container which has a capacity at least 25 percent greater than the container in which the sample is to be transported. Make sure both sample containers are clean and dry. Using clean, long-handled tongs, turn the sample collection container upside down and lower it into the coating reservoir. The mouth of the sample collection container should be at approximately the midpoint of the reservoir (do not take the sample from the top surface). Turn the sample collection container over and slowly bring it to the top of the coating reservoir. Rapidly pour the collected coating into the sample container, filling it completely. It is important to fill the sample container completely to avoid any loss of volatiles due to volatilization into the headspace. Return any unused coating to the reservoir or dispose as appropriate.
Note:
If a company requests a set of samples for its own analysis, a separate set of samples, using new sample containers, should be taken at the same time.
8.5Once the sample is collected, place the sample container on a firm surface and insert the inner seal in the container by placing the seal inside the rim of the container, inverting a screw cap, and pressing down on the screw cap which will evenly force the inner seal into the container for a tight fit. Using clean towels or rags, remove all residual coating material from the outside of the sample container after inserting the inner seal. Screw the cap onto the container.
8.5.1Affix a sample label (see Section 18) clearly identifying the sample, date collected, and person collecting the sample.
8.5.2Prepare the sample for transportation to the laboratory. The sample should be maintained at the coating's recommended storage temperature specified on the Material Safety Data Sheet, or, if no temperature is specified, the sample should be maintained within the range of 5 °C to 38 °C.
8.9The shipping container should adhere to U.S. Department of Transportation specification DOT 12-B. Coating samples are considered hazardous materials; appropriate shipping procedures should be followed.
9. Quality Control
9.1Laboratories using this method should operate a formal quality control program. The minimum requirements of the program should consist of an initial demonstration of laboratory capability and an ongoing analysis of blanks and quality control samples to evaluate and document quality data. The laboratory must maintain records to document the quality of the data generated. When results indicate atypical method performance, a quality control check standard (see Section 9.4) must be analyzed to confirm that the measurements were performed in an in-control mode of operation.
9.2Before processing any samples, the analyst must demonstrate, through analysis of a reagent blank, that there are no interferences from the analytical system, glassware, and reagents that would bias the sample analysis results. Each time a set of analytical samples is processed or there is a change in reagents, a reagent blank should be processed as a safeguard against chronic laboratory contamination. The blank samples should be carried through all stages of the sample preparation and measurement steps.
9.3Required instrument quality control parameters are found in the following sections:
9.3.1Baseline stability must be demonstrated to be ≤5 percent of full scale using the procedures given in Section 10.1.
9.3.2The GC calibration is not valid unless the retention time (RT) for each analyte at each concentration is within ±0.05 min of the retention time measured for that analyte in the stock standard.
9.3.3The retention time (RT) of any sample analyte must be within ±0.05 min of the average RT of the analyte in the calibration standards for the analyte to be considered tentatively identified.
9.3.4The GC system must be calibrated as specified in Section 10.2.
9.3.5A one-point daily calibration check must be performed as specified in Section 10.3.
9.4To establish the ability to generate results having acceptable accuracy and precision, the analyst must perform the following operations.
9.4.1Prepare a quality control check standard (QCCS) containing each analyte expected in the coating samples at a concentration expected to result in a response between 25 percent and 75 percent of the limits of the calibration curve when the sample is prepared as described in Section 11.5. The QCCS may be prepared from reference standard materials or purchased as certified solutions. If prepared in the laboratory, the QCCS must be prepared independently from the calibration standards.
9.4.2Analyze three aliquots of the QCCS according to the method beginning in Section 11.5.3 and calculate the weight percent of each analyte using Equation 1, Section 12.
9.4.3Calculate the mean weight percent (X) for each analyte from the three results obtained in Section 9.4.2.
9.4.4Calculate the percent accuracy for each analyte using the known concentrations (Ti) in the QCCS using Equation 3, Section 12.
9.4.5Calculate the percent relative standard deviation (percent RSD) for each analyte using Equation 7, Section 12, substituting the appropriate values for the relative response factors (RRF's) in said equation.
9.4.6If the percent accuracy (Section 9.4.4) for all analytes is within the range 90 percent to 110 percent and the percent RSD (Section 9.4.5) for all analytes is ≤20 percent, system performance is acceptable and sample analysis may begin. If these criteria are not met for any analyte, then system performance is not acceptable for that analyte and the test must be repeated for those analytes only. Repeated failures indicate a general problem with the measurement system that must be located and corrected. In this case, the entire test, beginning at Section 9.4.1, must be repeated after the problem is corrected.
9.5Great care must be exercised to maintain the integrity of all standards. It is recommended that all standards be stored at −10 °C to 0 °C in screw-cap amber glass bottles with Teflon liners.
9.6Unless otherwise specified, all weights are to be recorded within 0.1 mg.
10. Calibration and Standardization.
10.1Column Baseline Drift. Before each calibration and series of determinations and before the daily calibration check, condition the column using procedures developed by the laboratory or as specified by the column supplier. Operate the GC at initial (i.e., before sample injection) conditions on the lowest attenuation to be used during sample analysis. Adjust the recorder pen to zero on the chart and obtain a baseline for at least one minute. Initiate the GC operating cycle that would be used for sample analysis. On the recorder chart, mark the pen position at the end of the simulated sample analysis cycle. Baseline drift is defined as the absolute difference in the pen positions at the beginning and end of the cycle in the direction perpendicular to the chart movement. Calculate the percent baseline drift by dividing the baseline drift by the chart width representing full-scale deflection and multiply the result by 100.
10.2Calibration of GC. Bring all stock standards and calibration standards to room temperature while establishing the GC at the determined operating conditions.
10.2.1Retention Times (RT's) for Individual Compounds.
Note:
The procedures of this subsection are required only for the initial calibration. However, it is good laboratory practice to follow these procedures for some or all analytes before each calibration. The procedures were written for chromatograms output to a strip chart recorder. More modern instruments (e.g., integrators and electronic data stations) determine and print out or display retention times automatically.
The RT for each analyte should be determined before calibration. This provides a positive identification for each peak observed from the calibration standards. Inject an appropriate volume (see Note in Section 11.5.2) of one of the stock reference standards into the gas chromatograph and record on the chart the pen position at the time of the injection (see Section 7.6.1). Dilute an aliquot of the stock reference standard as required in dimethylformamide to achieve a concentration that will result in an on-scale response. Operate the gas chromatograph according to the determined procedures. Select the peak(s) that correspond to the analyte(s) [and internal standard, if used] and measure the retention time(s). If a chart recorder is used, measure the distance(s) on the chart from the injection point to the peak maxima. These distances, divided by the chart speed, are defined as the RT's of the analytes in question. Repeat this process for each of the stock reference standard solutions.
Note:
If gas chromatography with mass spectrometer detection (GC-MS) is used, a stock reference standard may contain a group of analytes, provided all analytes are adequately separated during the analysis. Mass spectral library matching can be used to identify the analyte associated with each peak in the gas chromatogram. The retention time for the analyte then becomes the retention time of its peak in the chromatogram.
10.2.2Calibration. The GC must be calibrated using a minimum of three concentration levels of each potential analyte. (See Section 7.7 for instructions on preparation of the calibration standards.) Beginning with the lowest concentration level calibration standard, carry out the analysis procedure as described beginning in Section 11.7. Repeat the procedure for each progressively higher concentration level until all calibration standards have been analyzed.
10.2.2.1Calculate the RT's for the internal standard and for each analyte in the calibration standards at each concentration level as described in Section 10.2.1. The RT's for the internal standard must not vary by more than 0.10 minutes. Identify each analyte by comparison of the RT's for peak maxima to the RT's determined in Section 10.2.1.
10.2.2.2Compare the retention times (RT's) for each potential analyte in the calibration standards for each concentration level to the retention times determined in Section 10.2.1. The calibration is not valid unless all RT's for all analytes meet the criteria given in Section 9.3.2.
10.2.2.3Tabulate the area responses and the concentrations for the internal standard and each analyte in the calibration standards. Calculate the response factor for the internal standard (RFis) and the response factor for each compound relative to the internal standard (RRF) for each concentration level using Equations 5 and 6, Section 12.
10.2.2.4Using the RRF's from the calibration, calculate the percent relative standard deviation (percent RSD) for each analyte in the calibration standard using Equation 7, Section 12. The percent RSD for each individual calibration analyte must be less than 15 percent. This criterion must be met in order for the calibration to be valid. If the criterion is met, the mean RRF's determined above are to be used until the next calibration.
10.3Daily Calibration Checks. The calibration curve (Section 10.2.2) must be checked and verified at least once each day that samples are analyzed. This is accomplished by analyzing a calibration standard that is at a concentration near the midpoint of the working range and performing the checks in Sections 10.3.1, 10.3.2, and 10.3.3.
10.3.1For each analyte in the calibration standard, calculate the percent difference in the RRF from the last calibration using Equation 8, Section 12. If the percent difference for each calibration analyte is less than 10 percent, the last calibration curve is assumed to be valid. If the percent difference for any analyte is greater than 5 percent, the analyst should consider this a warning limit. If the percent difference for any one calibration analyte exceeds 10 percent, corrective action must be taken. If no source of the problem can be determined after corrective action has been taken, a new three-point (minimum) calibration must be generated. This criterion must be met before quantitative analysis begins.
10.3.2If the RFis for the internal standard changes by more than ±20 percent from the last daily calibration check, the system must be inspected for malfunctions and corrections made as appropriate.
10.3.3The retention times for the internal standard and all calibration check analytes must be evaluated. If the retention time for the internal standard or for any calibration check analyte changes by more than 0.10 min from the last calibration, the system must be inspected for malfunctions and corrections made as required.
11. Procedure
11.1All samples and standards must be allowed to warm to room temperature before analysis. Observe the given order of ingredient addition to minimize loss of volatiles.
11.2Bring the GC system to the determined operating conditions and condition the column as described in Section 10.1.
Note:
The temperature of the injection port may be an especially critical parameter. Information about the proper temperature may be found on the CPDS.
11.3Perform the daily calibration checks as described in Section 10.3. Samples are not to be analyzed until the criteria in Section 10.3 are met.
11.4Place the as-received coating sample on a paint shaker, or similar device, and shake the sample for a minimum of 5 minutes to achieve homogenization.
11.5Note: The steps in this section must be performed rapidly and without interruption to avoid loss of volatile organics. These steps must be performed in a laboratory hood free from solvent vapors. All weights must be recorded to the nearest 0.1 mg.
11.5.1Add 16 g of dimethylformamide to each of two tared vials (A and B) capable of being septum sealed.
11.5.2To each vial add a weight of coating that will result in the response for the major constituent being in the upper half of the linear range of the calibration curve.
Note:
The magnitude of the response obviously depends on the amount of sample injected into the GC as specified in Section 11.8. This volume must be the same as used for preparation of the calibration curve, otherwise shifts in compound retention times may occur. If a sample is prepared that results in a response outside the limits of the calibration curve, new samples must be prepared; changing the volume injected to bring the response within the calibration curve limits is not permitted.
11.5.3Add a weight of internal standard to each vial (A and B) that will result in the response for the internal standard being between 25 percent and 75 percent of the linear range of the calibration curve.
11.5.4Seal the vials with crimp-on or Mininert ® septum seals.
11.6Shake the vials containing the prepared coating samples for 60 seconds. Allow the vials to stand undisturbed for ten minutes. If solids have not settled out on the bottom after 10 minutes, then centrifuge at 1,000 rpm for 5 minutes. The analyst also has the option of injecting the sample without allowing the solids to settle.
11.7Analyses should be conducted in the following order: daily calibration check sample, method blank, up to 10 injections from sample vials (i.e., one injection each from up to five pairs of vials, which corresponds to analysis of 5 coating samples).
11.8Inject the prescribed volume of supernatant from the calibration check sample, the method blank, and the sample vials onto the chromatographic column and record the chromatograms while operating the system under the specified operating conditions.
Note:
The analyst has the option of injecting the unseparated sample.
12. Data Analysis and Calculations
12.1 Qualitative Analysis. An analyte (e.g., those cited in Section 1.1) is considered tentatively identified if two criteria are satisfied: (1) elution of the sample analyte within ±0.05 min of the average GC retention time of the same analyte in the calibration standard; and (2) either (a) confirmation of the identity of the compound by spectral matching on a gas chromatograph equipped with a mass selective detector or (b) elution of the sample analyte within ±0.05 min of the average GC retention time of the same analyte in the calibration standard analyzed on a dissimilar GC column.
12.1.1 The RT of the sample analyte must meet the criteria specified in Section 9.3.3.
12.1.2 When doubt exists as to the identification of a peak or the resolution of two or more components possibly comprising one peak, additional confirmatory techniques (listed in Section 12.1) must be used.
12.2 Quantitative Analysis. When an analyte has been identified, the quantification of that compound will be based on the internal standard technique.
12.2.1 A single analysis consists of one injection from each of two sample vials (A and B) prepared using the same coating. Calculate the concentration of each identified analyte in the sample as follows:
12.2.2 Report results for duplicate analysis (sample vials A and B) without correction.
12.3 Precision Data. Calculate the percent difference between the measured concentrations of each analyte in vials A and B as follows.
12.3.1 Calculate the weight percent of the analyte in each of the two sample vials as described in Section 12.2.1.
12.3.2 Calculate the percent difference for each analyte as:
where Ai and Bi are the measured concentrations of the analyte in vials A and B.
12.4 Calculate the percent accuracy for analytes in the QCCS (See Section 9.4) as follows:
where Xx is the mean measured value and Tx is the known true value of the analyte in the QCCS.
12.5 Obtain retention times (RT's) from data station or integrator or, for chromatograms from a chart recorder, calculate the RT's for analytes in the calibration standards (See Section 10.2.2.2) as follows:
12.6 Calculate the response factor for the internal standard (See Section 10.2.2.3) as follows:
where:
Ais = Area response of the internal standard.
Cis = Weight percent of the internal standard.
12.7 Calculate the relative response factors for analytes in the calibration standards (See Section 10.2.2.3) as follows:
where:
RRFx = Relative response factor for an individual analyte.
Ax = Area response of the analyte being measured.
Cx = Weight percent of the analyte being measured.
12.8 Calculate the percent relative standard deviation of the relative response factors for analytes in the calibration standards (See Section 10.2.2.4) as follows:
12.9 Calculate the percent difference in the relative response factors between the calibration curve and the daily calibration checks (See Section 10.3) as follows:
13. Measurement of Reaction Byproducts That are HAP [Reserved]
14. Method Performance [Reserved]
15. Pollution Prevention [Reserved]
16. Waste Management
16.1 The coating samples and laboratory standards and reagents may contain compounds which require management as hazardous waste. It is the laboratory's responsibility to ensure all wastes are managed in accordance with all applicable laws and regulations.
16.2 To avoid excessive laboratory waste, obtain only enough sample for laboratory analysis.
16.3 It is recommended that discarded waste coating solids, used rags, used paper towels, and other nonglass or nonsharp waste materials be placed in a plastic bag before disposal. A separate container, designated “For Sharp Objects Only,” is recommended for collection of discarded glassware and other sharp-edge items used in the laboratory. It is recommended that unused or excess samples and reagents be placed in a solvent-resistant plastic or metal container with a lid or cover designed for flammable liquids. This container should not be stored in the area where analytical work is performed. It is recommended that a record be kept of all compounds placed in the container for identification of the contents upon disposal.
17. References
1. Clean Air Act Amendments, Public Law 101-549, Titles I-XI, November, 1990.
2. Standard Test Method for Water Content of Water-Reducible Paints by Direct Injection into a Gas Chromatograph. ASTM Designation D3792-79.
3. Standard Practice for Sampling Liquid Paints and Related Pigment Coatings. ASTM Designation D3925-81.
4. Standard Test Method for Determination of Dichloromethane and 1,1,1-Trichloroethane in Paints and Coatings by Direct Injection into a Gas Chromatograph. ASTM Designation D4457-85.
5. Standard Test Method for Determining the Unreacted Monomer Content of Latexes Using Capillary Column Gas Chromatography. ASTM Designation D4827-93.
6. Standard Test Method for Determining Unreacted Monomer Content of Latexes Using Gas-Liquid Chromatography. ASTM Designation D 4747-87.
7. Method 301—“Field Validation of Pollutant Measurement Methods from Various Waste Media,” 40 CFR 63, Appendix A.
8. “Reagent Chemicals, American Chemical Society Specifications,” American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see “Reagent Chemicals and Standards” by Joseph Rosin, D. Van Nostrand Co., Inc., New York, NY and the “United States Pharmacopeia.”
18. Tables, Diagrams, Flowcharts, and Validation Data
Agency:
Inspector:
Date/Time:
Sample ID#:
Source ID:
Coating Name/Type:
Plant Witness:
Type Analysis Required:
Special Handling:
Sample Container Label
Coating Data
Date:
Source:
Data Sample ID No. Sample ID No.
Coating:
Supplier Name
Name and Color of Coating
Type of Coating (primer, clearcoat, etc.)
Identification Number for Coating
Coating Density (lbs/gal)
Total Volatiles Content (wt percent)
Water Content (wt percent)
Exempt Solvents Content (wt percent)
VOC Content (wt percent)
Solids Content (vol percent)
Diluent Properties:
Name
Identification Number
Diluent Solvent Density (lbs/gal)
VOC Content (wt percent)
Water Content (wt percent)
Exempt Solvent Content (wt percent)
Diluent/Solvent Ratio (gal diluent solvent/gal coating)
Stock Reference Standard
Name of Reference Material:
Supplier Name:
Lot Number:
Purity:
Name of Solvent Material: Dimethylformamide
Supplier Name:
Lot Number:
Purity:
Date Prepared:
Prepared By:
Notebook/page no.:
Preparation Information
1. Weight Empty Flask ____,g
2. Weight Plus DMF ____,g
3. Weight Plus Reference Material ____,g
4. Weight After Made to Volume ____,g
5. Weight DMF (lines 2-1 3-4) ____,g
6. Weight Ref. Material (lines 3-2) ____,g
7. Corrected Weight of Reference Material (line 6 times purity) ____,g
8. Fraction Reference Material in Standard (Line 7 ÷ Line 5) soln ____,g/g
9. Total Volume of Standard Solution ____, ml
10. Weight Reference Material per ml of Solution (Line 7 ÷ Line 9) ____,g/ml
Laboratory ID No. for this Standard ____
Expiration Date for this Standard ____
CALIBRATION STANDARD
Date Prepared:
Date Expires:
Prepared By:
Notebook/page:
Calibration Standard Identification No.:
Preparation Information
Final Weight Flask Plus Reagents ____, g
Weight Empty Flask ____, g
Total Weight Of Reagents ____, g
Analyte name a Stock reference standard ID No. Amount of stock reference standard added (by volume or by weight) Calculated weight analyte added, g Weight percent analyte in calibration standard b
Volume added, ml Amount in standard, g/ml Weight added, g Amount in standard, g/g soln
a Include internal standard(s).
b Weight percent = weight analyte added ÷ total weight of reagents.
Quality Control Check Standard
Date Prepared:
Date Expires:
Prepared By:
Notebook/page:
Quality Control Check Standard Identification No.:
Preparation Information
Final Weight Flask Plus Reagents ____,g
Weight Empty Flask ____,g
Total Weight Of Reagents ____,g
Analyte name a Stock reference standard ID No. Amount of stock reference standard added (by volume or by weight) Calculated weight analyte added, g Weight percent analyte in QCC standard b
Volume added, ml Amount in standard, g/ml Weight added, g Amount in standard, g/g soln
a Include internal Standard(s).
b Weight percent=weight analyte added ÷ total weight of reagents.
Quality Control Check Standard Analysis
Date OCCS Analyzed:
OCCS Identification No.
Analyst:
QCC Expiration Date:
Analysis Results
Analyte Weight percent determined Mean Wt percent Percent accuracx Percent RSD Meets criteria in Section 9.4.6
Run 1 Run 2 Run 3 Percentaccuracy Percent RSD
Calibration of Gas Chromatograph
Calibration Date:
Calibrated By:
Part 1 —Retention Times for Individual Analytes
Analyte Stock standard. ID No. Recorder chart speed Distance from injection point to peak maximum Retention time, minutes a
Inches/min. cm/min. Inches Centimeters
a Retention time=distance to peak maxima÷chart speed.
CALIBRATION OF GAS CHROMATOGRAPH
Calibration Date:
Calibrated By:
Part 2 —Analysis of Calibration Standards
Analyte Calib. STD ID No. Calib. STD ID No. Calib. STD ID No.
Name:
Conc. in STD
Area Response
RT
Name:
Conc. in STD
Area Response
RT
Name:
Conc. in STD
Area Response
RT
Name:
Conc. in STD
Area Response
RT
Name:
Conc. in STD
Area Response
RT
Name:
Conc. in STD
Area Response
RT
Name:
Conc. in STD
Area Response
RT
Name:
Conc. in STD
Area Response
RT
Internal Standard Name:
Conc. in STD
Area Response
RT
Calibration of Gas Chromatograph
Calibration Date:
Calibrated By:
Part 3 —Data Analysis for Calibration Standards
Analyte Calib. STD ID Calib. STD ID Calib. STD ID Mean percent RSD of RF Is RT within ±0.05 min of RT for stock? (Y/N) Is percent RSD <30% (Y/N)
Name:
RT
RF
Name:
RT
RF
Name:
RT
RF
Name:
RT
RF
Name:
RT
RF
Name:
RT
RF
Name:
RT
RF
Daily Calibration Check
Date:
Analyst:
Calibration Check Standard ID No.:
Expiration Date:
Analyte Retention Time (RT) Response Factor (RF)
Last This Difference a Last This Difference b
a Retention time (RT) change (difference) must be less than ±0.10 minutes.
b Response factor (RF) change (difference) must be less than 20 percent for each analyte and for the internal standard.
Sample Analysis
Vial A ID No.:
Vial B ID No.:
Analyzed By:
Date:
Sample preparation information Vial A (g) Vial B (g)
Measured:
wt empty via
wt plus DMF
wt plus sample
wt plus internal
standard
Calculated:
wt DMF
wt sample
wt internal standard
Analysis Results: Duplicate Samples
Analyte Area response RF Wt percent in sample
Vial A Vial B Vial A Vial B Average
Internal Standard
Method 312A—Determination of Styrene in Latex Styrene-Butadiene Rubber, Through Gas Chromatography
1.Scope and Application
1.1This method describes a procedure for determining parts per million (ppm) styrene monomer (CAS No. 100-42-5) in aqueous samples, including latex samples and styrene stripper water.
1.2The sample is separated in a gas chromatograph equipped with a packed column and a flame ionization detector.
2.0Summary of Method
2.1This method utilizes a packed column gas chromatograph with a flame ionization detector to determine the concentration of residual styrene in styrene butadiene rubber (SBR) latex samples.
3.0Definitions
3.1The definitions are included in the text as needed.
4.0Interferences
4.1In order to reduce matrix effects and emulsify the styrene, similar styrene free latex is added to the internal standard. There are no known interferences.
4.2The operating parameters are selected to obtain resolution necessary to determine styrene monomer concentrations in latex.
5.0Safety
5.1It is the responsibility of the user of this procedure to establish appropriate safety and health practices.
6.0Equipment and Supplies
6.1Adjustable bottle-top dispenser, set to deliver 3 ml. (for internal standard), Brinkmann Dispensette, or equivalent.
6.2Pipettor, set to 10 ml., Oxford Macro-set, or equivalent.
6.3Volumetric flask, 100-ml, with stopper.
6.4Hewlett Packard Model 5710A dual channel gas chromatograph equipped with flame ionization detector.
6.4.111 ft. × 1/8 in. stainless steel column packed with 10% TCEP on 100/120 mesh Chromosorb P, or equivalent.
6.4.2Perkin Elmer Model 023 strip chart recorder, or equivalent.
6.5Helium carrier gas, zero grade.
6.6Liquid syringe, 25-µl.
6.7Digital MicroVAX 3100 computer with VG Multichrom software, or equivalent data handling system.
6.6Wire Screens, circular, 70-mm, 80-mesh diamond weave.
6.7DEHA—(N,N-Diethyl hydroxylamine), 97 % purity, CAS No. 3710-84-7
6.8p-Dioxane, CAS No. 123-91-1
7.0Reagents and Standards
7.1Internal standard preparation.
7.1.1Pipette 5 ml p-dioxane into a 1000-ml volumetric flask and fill to the mark with distilled water and mix thoroughly.
7.2Calibration solution preparation.
7.2.1Pipette 10 ml styrene-free latex (eg: NBR latex) into a 100-ml volumetric flask.
7.2.2Add 3 ml internal standard (section 7.1.1 of this method).
7.2.3Weigh exactly 10 µl fresh styrene and record the weight.
7.2.4Inject the styrene into the flask and mix well.
7.2.5Add 2 drops of DEHA, fill to the mark with water and mix well again.
7.2.6Calculate concentration of the calibration solution as follows:
mg/l styrene=(mg styrene added)/0.1 L
8.0Sample Collection, Preservation, and Storage
8.1A representative SBR emulsion sample should be caught in a clean, dry 6-oz. teflon lined glass container. Close it properly to assure no sample leakage.
8.2The container should be labeled with sample identification, date and time.
9.0Quality Control
9.1The instrument is calibrated by injecting calibration solution (Section 7.2 of this method) five times.
9.2The retention time for components of interest and relative response of monomer to the internal standard is determined.
9.3Recovery efficiency must be determined once for each sample type and whenever modifications are made to the method.
9.3.1A set of six latex samples shall be collected. Two samples shall be prepared for analysis from each sample. Each sample shall be analyzed in duplicate.
9.3.2The second set of six latex samples shall be analyzed in duplicate before spiking each sample with approximately 1000 ppm styrene. The spiked samples shall be analyzed in duplicate.
9.3.3For each hydrocarbon, calculate the average recovery efficiency (R) using the following equations:
where:
R=Σ(Rn)/6
where:
Rn=(cns−cv)/Sn
n=sample number
cns=concentration of compound measured in spiked sample number n.
cnu= concentration of compound measured in unspiked sample number n.
Sn=theoretical concentration of compound spiked into sample n.
9.3.4A value of R between 0.70 and 1.30 is acceptable.
9.3.5R is used to correct all reported results for each compound by dividing the measured results of each compound by the R for that compound for the same sample type.
10.0Calibration and Instrument Settings
10.1Injection port temperature, 250 °C.
10.2Oven temperature, 110 °C, isothermal.
10.3Carrier gas flow, 25 cc/min.
10.4Detector temperature, 250 °C.
10.5Range, 1X.
11.0Procedure
11.1Turn on recorder and adjust baseline to zero.
11.2Prepare sample.
11.2.1For latex samples, add 3 ml Internal Standard (section 7.1 of this method) to a 100-ml volumetric flask. Pipet 10 ml sample into the flask using the Oxford pipettor, dilute to the 100-ml mark with water, and shake well.
11.2.2For water samples, add 3 ml Internal Standard (section 7.1 of this method) to a 100-ml volumetric flask and fill to the mark with sample. Shake well.
11.3Flush syringe with sample.
11.4Carefully inject 2 µl of sample into the gas chromatograph column injection port and press the start button.
11.5When the run is complete the computer will print a report of the analysis.
12.0Data Analysis and Calculation
12.1For samples that are prepared as in section 11.2.1 of this method:
ppm styrene = A×D
Where:
A = “ppm” readout from computer
D = dilution factor (10 for latex samples)
12.2For samples that are prepared as in section 11.2.2 of this method, ppm styrene is read directly from the computer.
13.0Method Performance
13.1This test has a standard deviation (1) of 3.3 ppm at 100 ppm styrene. The average Spike Recovery from six samples at 1000 ppm Styrene was 96.7 percent. The test method was validated using 926 ppm styrene standard. Six analysis of the same standard provided average 97.7 percent recovery. Note: These are example recoveries and do not replace quality assurance procedures in this method.
14.0Pollution Prevention
14.1Waste generation should be minimized where possible. Sample size should be an amount necessary to adequately run the analysis.
15.0Waste Management
15.1All waste shall be handled in accordance with Federal and State environmental regulations.
16.0References and Publications
16.140 CFR 63 Appendix A—Method 301 Test Methods Field Validation of Pollutant Measurement
16.2DSM Copolymer Test Method T-3060, dated October 19, 1995, entitled: Determination of Residual Styrene in Latex, Leonard, C.D., Vora, N.M.et al
Method 312B—Determination of Residual Styrene in Styrene-Butadiene (SBR) Rubber Latex by Capillary Gas Chromatography
1.0Scope
1.1This method is applicable to SBR latex solutions.
1.2This method quantitatively determines residual styrene concentrations in SBR latex solutions at levels from 80 to 1200 ppm.
2.0Principle of Method
2.1A weighed sample of a latex solution is coagulated with an ethyl alcohol (EtOH) solution containing a specific amount of alpha-methyl styrene (AMS) as the internal standard. The extract of this coagulation is then injected into a gas chromatograph and separated into individual components. Quantification is achieved by the method of internal standardization.
3.0Definitions
3.1The definitions are included in the text as needed.
4.0Interferences [Reserved]
5.0Safety
5.1This method may involve hazardous materials, operations, and equipment. This method does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this method to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
6.0Equipment and Supplies
6.1Analytical balance, 160 g capacity, and 0.1 mg resolution
6.2Bottles, 2-oz capacity, with poly-cap screw lids
6.3Mechanical shaker
6.4Syringe, 10-ul capacity
6.5Gas chromatograph, Hewlett Packard model 5890A, or equivalent, configured with FID with a megabore jet, splitless injector packed with silanized glass wool.
6.5.1Establish the following gas chromatographic conditions, and allow the system to thoroughly equilibrate before use.
Injection technique = Splitless
Injector temperature = 225 deg C
Oven temperature = 70 deg C (isothermal)
Detector: temperature = 300 deg C
range = 5
attenuation = 0
Carrier gas: helium = 47 ml/min
Detector gases: hydrogen = 30 ml/min
air = 270 ml/min
make-up = 0 ml/min
Analysis time: = 3.2 min at the specified carrier gas flow rate and column temperature.
6.6Gas chromatographic column, DB-1, 30 M X 0.53 ID, or equivalent, with a 1.5 micron film thickness.
6.7Data collection system, Perkin-Elmer/Nelson Series Turbochrom 4 Series 900 Interface, or equivalent.
6.8Pipet, automatic dispensing, 50-ml capacity, and 2-liter reservoir.
6.9Flasks, volumetric, class A, 100-ml and 1000-ml capacity.
6.10Pipet, volumetric delivery, 10-ml capacity, class A.
7.0Chemicals and Reagents
CHEMICALS:
7.1Styrene, C8H8, 99 %, CAS 100-42-5
7.2Alpha methyl styrene, C9H10, 99%, CAS 98-83-9
7.3Ethyl alcohol, C2H5OH, denatured formula 2B, CAS 64-17-5
REAGENTS:
7.4Internal Standard Stock Solution: 5.0 mg/ml AMS in ethyl alcohol.
7.4.1Into a 100-ml volumetric flask, weigh 0.50 g of AMS to the nearest 0.1 mg.
7.4.2Dilute to the mark with ethyl alcohol. This solution will contain 5.0 mg/ml AMS in ethyl alcohol and will be labeled the AMS STOCK SOLUTION.
7.5Internal Standard Working Solution: 2500 ug/50 ml of AMS in ethyl alcohol.
7.5.1Using a 10 ml volumetric pipet, quantitatively transfer 10.0 ml of the AMS STOCK SOLUTION into a 1000-ml volumetric flask.
7.5.2Dilute to the mark with ethyl alcohol. This solution will contain 2500 ug/50ml of AMS in ethyl alcohol and will be labeled the AMS WORKING SOLUTION.
7.5.3Transfer the AMS WORKING SOLUTION to the automatic dispensing pipet reservoir.
7.6Styrene Stock Solution: 5.0 mg/ml styrene in ethyl alcohol.
7.6.1Into a 100-ml volumetric flask, weigh 0.50 g of styrene to the nearest 0.1 mg.
7.6.2Dilute to the mark with ethyl alcohol. This solution will contain 5.0 mg/ml styrene in ethyl alcohol and will be labeled the STYRENE STOCK SOLUTION.
7.7Styrene Working Solution: 5000 ug/10 ml of styrene in ethyl alcohol.
7.7.1Using a 10-ml volumetric pipet, quantitatively transfer 10.0 ml of the STYRENE STOCK SOLUTION into a 100-ml volumetric flask.
7.7.2Dilute to the mark with ethyl alcohol. This solution will contain 5000 ug/10 ml of styrene in ethyl alcohol and will be labeled the STYRENE WORKING SOLUTION.
8.0Sample Collection, Preservation and Storage
8.1Label a 2-oz sample poly-cap lid with the identity, date and time of the sample to be obtained.
8.2At the sample location, open sample valve for at least 15 seconds to ensure that the sampling pipe has been properly flushed with fresh sample.
8.3Fill the sample jar to the top (no headspace) with sample, then cap it tightly.
8.4Deliver sample to the Laboratory for testing within one hour of sampling.
8.5Laboratory testing will be done within two hours of the sampling time.
8.6No special storage conditions are required unless the storage time exceeds 2 hours in which case refrigeration of the sample is recommended.
9.0Quality Control
9.1For each sample type, 12 samples of SBR latex shall be obtained from the process for the recovery study. Half the vials and caps shall be tared, labeled “spiked”, and numbered 1 through 6. The other vials are labeled “unspiked” and need not be tared, but are also numbered 1 through 6.
9.2The six vials labeled “spiked” shall be spiked with an amount of styrene to approximate 50% of the solution's expected residual styrene level.
9.3The spiked samples shall be shaken for several hours and allowed to cool to room temperature before analysis.
9.4The six samples of unspiked solution shall be coagulated and a mean styrene value shall be determined, along with the standard deviation, and the percent relative standard deviation.
9.5The six samples of the spiked solution shall be coagulated and the results of the analyses shall be determined using the following equations:
Mr=Ms−Mu
R=Mr/S
where:
Mu=Mean value of styrene in the unspiked sample
Ms=Measured amount of styrene in the spiked sample
Mr=Measured amount of the spiked compound
S=Amount of styrene added to the spiked sample
R=Fraction of spiked styrene recovered
9.6A value of R between 0.70 and 1.30 is acceptable.
9.7R is used to correct all reported results for each compound by dividing the measured results of each compound by the R for that compound for the same sample type.
10.0Calibration
10.1Using a 10-ml volumetric pipet, quantitatively transfer 10.0 ml of the STYRENE WORKING SOLUTION (section 7.7.2 of this method) into a 2-oz bottle.
10.2Using the AMS WORKING SOLUTION equipped with the automatic dispensing pipet (section 7.5.3 of this method), transfer 50.0 ml of the internal standard solution into the 2-oz bottle.
10.3Cap the 2-oz bottle and swirl. This is the calibration standard, which contains 5000 µg of styrene and 2500 µg of AMS.
10.4Using the conditions prescribed (section 6.5 of this method), chromatograph 1 µl of the calibration standard.
10.5Obtain the peak areas and calculate the relative response factor as described in the calculations section (section 12.1 of this method).
11.0Procedure
11.1Into a tared 2-oz bottle, weigh 10.0 g of latex to the nearest 0.1 g.
11.2Using the AMS WORKING SOLUTION equipped with the automatic dispensing pipet (section 7.5.3 of this method), transfer 50.0 ml of the internal standard solution into the 2-oz bottle.
11.3Cap the bottle. Using a mechanical shaker, shake the bottle for at least one minute or until coagulation of the latex is complete as indicated by a clear solvent.
11.4Using the conditions prescribed (section 6.5 of this method), chromatograph 1 ul of the liquor.
11.5Obtain the peak areas and calculate the concentration of styrene in the latex as described in the calculations section (Section 12.2 of this method).
12.0Calculations
12.1Calibration:
RF=(Wx×Ais) / (Wis×Ax)
where:
RF=the relative response factor for styrene
Wx=the weight (ug) of styrene
Ais=the area of AMS
Wis=the weight (ug) of AMS
Ax=the area of styrene
12.2Procedure:
ppmstyrene=(Ax RF×Wis) / (Ais×Ws)
where:
ppmstyrene=parts per million of styrene in the latex
Ax=the area of styrene
RF=the response factor for styrene
Wis=the weight (ug) of AMS
Ais=the area of AMS
Ws=the weight (g) of the latex sample
12.3Correct for recovery (R) as determined by section 9.0 of this method.
13.0Precision
13.1Precision for the method was determined at the 80, 144, 590, and 1160 ppm levels. The standard deviations were 0.8, 1.5, 5 and 9 ppm respectively. The percent relative standard deviations (%RSD) were 1% or less at all levels. Five degrees of freedom were used for all precision data except at the 80 ppm level, where nine degrees of freedom were used. Note: These are example results and do not replace quality assurance procedures in this method.
14.0Pollution Prevention
14.1Waste generation should be minimized where possible. Sample size should be an amount necessary to adequately run the analysis.
15.0Waste Management
15.1Discard liquid chemical waste into the chemical waste drum.
15.2Discard latex sample waste into the latex waste drum.
15.3Discard polymer waste into the polymer waste container.
16.0References
16.1This method is based on Goodyear Chemical Division Test Method E-889.
Method 312C—Determination of Residual Styrene in SBR Latex Produced by Emulsion Polymerization
1.0Scope
1.1This method is applicable for determining the amount of residual styrene in SBR latex as produced in the emulsion polymerization process.
2.0Principle of Method
2.1A weighed sample of latex is coagulated in 2-propanol which contains alpha-methyl styrene as an Internal Standard. The extract from the coagulation will contain the alpha-methyl styrene as the Internal Standard and the residual styrene from the latex. The extract is analyzed by a Gas Chromatograph. Percent styrene is calculated by relating the area of the styrene peak to the area of the Internal Standard peak of known concentration.
3.0Definitions
3.1The definitions are included in the text as needed.
4.0Interferences [Reserved]
5.0Safety
5.1When using solvents, avoid contact with skin and eyes. Wear hand and eye protection. Wash thoroughly after use.
5.2Avoid overexposure to solvent vapors. Handle only in well ventilated areas.
6.0Equipment and Supplies
6.1Gas Chromatograph—Hewlett Packard 5890, Series II with flame ionization detector, or equivalent.
Column—HP 19095F-123, 30m × 0.53mm, or equivalent. Substrate HP FFAP (cross-linked) film thickness 1 micrometer. Glass injector port liners with silanized glass wool plug.
Integrator—HP 3396, Series II, or equivalent.
6.2Wrist action shaker
6.3Automatic dispenser
6.4Automatic pipet, calibrated to deliver 5.0 ±0.01 grams of latex
6.5Four-ounce wide-mouth bottles with foil lined lids
6.6Crimp cap vials, 2ml, teflon lined septa
6.7Disposable pipets
6.8Qualitative filter paper
6.9Cap crimper
6.10Analytical balance
6.1110ml pipette
6.12Two-inch funnel
7.0Reagents and Standards
7.12-Propanol (HP2C grade)
7.2Alpha methyl styrene (99 % purity)
7.3Styrene (99 % purity)
7.4Zero air
7.5Hydrogen (chromatographic grade)
7.6Helium
7.7Internal Standard preparation
7.7.1Weigh 5.000-5.005 grams of alpha-methyl styrene into a 100ml volumetric flask and bring to mark with 2-propanol to make Stock “A” Solution.
Note:
Shelf life—6 months.
7.7.2Pipette 10ml of Stock “A” Solution into a 100ml volumetric flask and bring to mark with 2-propanol to prepare Stock “B” Solution.
7.7.3Pipette 10ml of the Stock “B” solution to a 1000ml volumetric flask and bring to the mark with 2-propanol. This will be the Internal Standard Solution (0.00005 grams/ml).
7.8Certification of Internal Standard—Each batch of Stock “B” Solution will be certified to confirm concentration.
7.8.1Prepare a Standard Styrene Control Solution in 2-propanol by the following method:
7.8.1.1Weigh 5.000 ±.005g of styrene to a 100ml volumetric flask and fill to mark with 2-propanol to make Styrene Stock “A” Solution.
7.8.1.2Pipette 10ml of Styrene Stock “A” Solution to a 100ml volumetric flask and fill to mark with 2-propanol to make Styrene Stock “B” Solution.
7.8.1.3Pipette 10ml of Styrene Stock “B” soluion to a 250ml volumtric flask and fill to mark wtih 2-propanol to make the Certification Solution.
7.8.2Certify Alpha-Methyl Styrene Stock “B” Solution.
7.8.2.1Pipette 5ml of the Certification Solution and 25ml of the Alpha Methyl Styrene Internal Standard Solution to a 4-oz. bottle, cap and shake well.
7.8.2.2Analyze the resulting mixture by GC using the residual styrene method. (11.4-11.6 of this method)
7.8.2.3Calculate the weight of alpha methyl styrene present in the 25ml aliquat of the new Alpha Methyl Styrene Standard by the following equation:
Wx = Fx xWis(Ax/Ais)
Where
Ax = Peak area of alpha methyl styrene
Ais = Peak area of styrene
Wx = Weight of alpha methyl styrene
Wis = Weight of styrene (.00100)
Fx = Analyzed response factor = 1
The Alpha Methyl Styrene Stock Solution used to prepare the Internal Standard Solution may be considered certified if the weight of alpha methyl styrene analyzed by this method is within the range of .00121g to .00129g.
8.0Sampling
8.1Collect a latex sample in a capped container. Cap the bottle and identify the sample as to location and time.
8.2Deliver sample to Laboratory for testing within one hour.
8.3Laboratory will test within two hours.
8.4No special storage conditions are required.
9.0Quality Control
9.1The laboratory is required to operate a formal quality control program. This consists of an initial demonstration of the capability of the method as well as ongoing analysis of standards, blanks, and spiked samples to demonstrate continued performance.
9.1.1When the method is first set up, a calibration is run and the recovery efficiency for each type of sample must be determined.
9.1.2If new types of samples are being analyzed, then recovery efficiency for each new type of sample must be determined. New type includes any change, such as polymer type, physical form or a significant change in the composition of the matrix.
9.2Recovery efficiency must be determined once for each sample type and whenever modifications are made to the method.
9.2.1 In determining the recovery efficiency, the quadruplet sampling system shall be used. Six sets of samples (for a total of 24) shall be taken. In each quadruplet set, half of the samples (two out of the four) shall be spiked with styrene.
9.2.2 Prepare the samples as described in section 8 of this method. To the vials labeled “spiked”, add a known amount of styrene that is expected to be present in the latex.
9.2.3 Run the spiked and unspiked samples in the normal manner. Record the concentrations of styrene reported for each pair of spiked and unspiked samples with the same vial number.
9.2.4 For each hydrocarbon, calculate the average recovery efficiency (R) using the following equation:
R=Σ(Rn)/12
Where: n = sample number
Rn=(Ms−Mu)/S
Ms=total mass of compound (styrene) measured in spiked sample (µg)
Mu=total mass of compound (styrene) measured in unspiked sample (µg)
S=theoretical mass of compound (styrene) spiked into sample (µg)
R=fraction of spiked compound (styrene) recovered
9.2.5A different R value should be obtained for each sample type. A value of R between 0.70 and 1.30 is acceptable.
9.2.6 Ris used to correct all reported results for each compound by dividing the measured results of each compound by the R for that compound for the same sample type.
10.0Calibration
A styrene control sample will be tested weekly to confirm the FID response and calibration.
10.1Using the Styrene Certification Solution prepared in 7.8.1, perform test analysis as described in 7.8.2 using the equation in 7.8.2.3 to calculate results.
10.2Calculate the weight of styrene in the styrene control sample using the following equation:
Wsty=(Fx xAsty xWis)Ais
The instrument can be considered calibrated if the weight of the styrene analyzed is within range of 0.00097-0.00103gms.
11.0Procedure
11.1Using an auto pipet, add 25ml of Internal Standard Solution to a 4 oz. wide-mouth bottle.
11.2Using a calibrated auto pipet, add 5.0 ±0.01g latex to the bottle containing the 25ml of Internal Standard Solution.
11.3Cap the bottle and place on the wrist action shaker. Shake the sample for a minimum of five minutes using the timer on the shaker. Remove from shaker.
11.4Using a disposable pipet, fill the 2ml sample vial with the clear alcohol extract. (If the extract is not clear, it should be filtered using a funnel and filter paper.) Cap and seal the vial.
11.5Place the sample in the autosampler tray and start the GC and Integrator. The sample will be injected into the GC by the auto-injector, and the Integrator will print the results.
11.6Gas Chromatograph Conditions
Oven Temp—70 °C
Injector Temp—225 °C
Detector Temp—275 °C
Helium Pressure—500 KPA
Column Head Pressure—70 KPA
Makeup Gas—30 ml/min.
Column—HP 19095F—123, 30m×0.53mm Substrate: HP—FFAP (cross-linked) 1 micrometer film thickness
12.0Calculations
12.1The integrator is programmed to do the following calculation at the end of the analysis:
%ResidualStyrene=(Ax XWis)/(Ais XWx)XFx X100
Where:
Ax=Peak area of styrene
Ais=Peak area of internal standard
Wx=Weight of sample = 5g
Wis=Weight of internal std. = 0.00125g
Fx=Analyzed response factor = 1.0
12.2The response factor is determined by analyzing a solution of 0.02g of styrene and 0.02g of alpha methyl styrene in 100ml of 2-propanol. Calculate the factor by the following equation:
Fx=(Wx xAis)/(Wis xAx)
Where:
Wx=Weight of styrene
Ax=Peak area of styrene
Wis=Weight of alpha methyl styrene
Ais=Peak area of alpha methyl styrene
13.0Method Performance
13.1Performance must be determined for each sample type by following the procedures in section 9 of this method.
14.0Waste Generation
14.1Waste generation should be minimized where possible.
15.0Waste Management
15.1All waste shall be handled in accordance with Federal and State environmental regulations.
16.0References [Reserved]
Method 313A—Determination of Residual Hydrocarbons in Rubber Crumb
1.0Scope and Application
1.1This method determines residual toluene and styrene in stripper crumb of the of the following types of rubber: polybutadiene (PBR) and styrene/butadiene rubber (SBR), both derived from solution polymerization processes that utilize toluene as the polymerization solvent.
1.2The method is applicable to a wide range of concentrations of toluene and styrene provided that calibration standards cover the desired range. It is applicable at least over the range of 0.01 to 10.0 % residual toluene and from 0.1 to 3.0 % residual styrene. It is probably applicable over a wider range, but this must be verified prior to use.
1.3The method may also be applicable to other process samples as long as they are of a similar composition to stripper crumb. See section 3.1 of this method for a description of stripper crumb.
2.0Summary of Method
2.1The wet crumb is placed in a sealed vial and run on a headspace sampler which heats the vial to a specified temperature for a specific time and then injects a known volume of vapor into a capillary GC. The concentration of each component in the vapor is proportional to the level of that component in the crumb sample and does not depend on water content of the crumb.
2.2Identification of each component is performed by comparing the retention times to those of known standards.
2.3Results are calculated by the external standard method since injections are all performed in an identical manner. The response for each component is compared with that obtained from dosed samples of crumb.
2.4Measured results of each compound are corrected by dividing each by the average recovery efficiency determined for the same compound in the same sample type.
3.0Definitions
3.1Stripper crumb refers to pieces of rubber resulting from the steam stripping of a toluene solution of the same polymer in a water slurry. The primary component of this will be polymer with lesser amounts of entrained water and residual toluene and other hydrocarbons. The amounts of hydrocarbons present must be such that the crumb is a solid material, generally less that 10 % of the dry rubber weight.
4.0Interferences
4.1Contamination is not normally a problem since samples are sealed into vials immediately on sampling.
4.2Cross contamination in the headspace sampler should not be a problem if the correct sampler settings are used. This should be verified by running a blank sample immediately following a normal or high sample. Settings may be modified if necessary if this proves to be a problem, or a blank sample may be inserted between samples.
4.3Interferences may occur if volatile hydrocarbons are present which have retention times close to that of the components of interest. Since the solvent makeup of the processes involved are normally fairly well defined this should not be a problem. If it is found to be the case, switching to a different chromatographic column will probably resolve the situation.
5.0Safety
5.1The chemicals specified in this method should all be handled according to standard laboratory practices as well as any special precautions that may be listed in the MSDS for that compound.
5.2Sampling of strippers or other process streams may involve high pressures and temperatures or may have the potential for exposure to chemical fumes. Only personnel who have been trained in the specific sampling procedures required for that process should perform this operation. An understanding of the process involved is necessary. Proper personal protective equipment should be worn. Any sampling devices should be inspected prior to use. A detailed sampling procedure which specifies exactly how to obtain the sample must be written and followed.
6.0Equipment and Supplies
6.1Hewlett Packard (HP) 7694 Headspace sampler, or equivalent, with the following conditions:
Times (min.): GC cycle time 6.0 , vial equilibration 30.0 , pressurization 0.25 , loop fill 0.25, loop equilibration 0.05 , inject 0.25
Temperatures (deg C): oven 70, loop 80, transfer line 90
Pressurization gas: He @ 16 psi
6.2HP 5890 Series II capillary gas chromatograph, or equivalent, with the following conditions:
Column: Supelco SPB-1, or equivalent, 15m × .25mm × .25 µ film
Carrier: He @ 6 psi
Run time: 4 minutes
Oven: 70 deg C isothermal
Injector: 200 deg C split ratio 50:1
Detector: FID @ 220 deg C
6.3HP Chemstation consisting of computer, printer and Chemstation software, or an equivalent chromatographic data system.
6.420 ml headspace vials with caps and septa.
6.5Headspace vial crimper.
6.6Microliter pipetting syringes.
6.7Drying oven at 100 deg C vented into cold trap or other means of trapping hydrocarbons released.
6.8Laboratory shaker or tumbler suitable for the headspace vials.
6.9Personal protective equipment required for sampling the process such as rubber gloves and face and eye protection.
7.0Reagents and Standards
7.1Toluene, 99.9 % purity, HPLC grade.
7.2Styrene, 99.9 % purity, HPLC grade.
7.3Dry rubber of same type as the stripper crumb samples.
8.0Sample Collection, Preservation and Storage
8.1Collect a sample of crumb in a manner appropriate for the process equipment being sampled.
8.1.1If conditions permit, this may be done by passing a stream of the crumb slurry through a strainer, thus separating the crumb from the water. Allow the water to drain freely, do not attempt to squeeze any water from the crumb. Results will not depend on the exact water content of the samples. Immediately place several pieces of crumb directly into a headspace vial. This should be done with rubber gloves to protect the hands from both the heat and from contact with residual hydrocarbons. The vial should be between 1/4 and 1/3 full. Results do not depend on sample size as long as there is sufficient sample to reach an equilibrium vapor pressure in the headspace of the vial. Cap and seal the vial. Prepare each sample at least in duplicate. This is to minimize the effect of the variation that naturally occurs in the composition of non homogeneous crumb. The free water is not analyzed by this method and should be disposed of appropriately along with any unused rubber crumb.
8.1.2Alternatively the process can be sampled in a specially constructed sealed bomb which can then be transported to the laboratory. The bomb is then cooled to ambient temperature by applying a stream of running water. The bomb can then be opened and the crumb separated from the water and the vials filled as described in section 8.1.1 of this method. The bomb may be stored up to 8 hours prior to transferring the crumb into vials.
8.2The sealed headspace vials may be run immediately or may be stored up to 72 hours prior to running. It is possible that even longer storage times may be acceptable, but this must be verified for the particular type of sample being analyzed (see section 9.2.3 of this method). The main concern here is that some types of rubber eventually may flow, thus compacting the crumb so that the surface area is reduced. This may have some effect on the headspace equilibration.
9.0Quality Control
9.1The laboratory is required to operate a formal quality control program. This consists of an initial demonstration of the capability of the method as well as ongoing analysis of standards, blanks and spiked samples to demonstrate continued performance.
9.1.1When the method is first set up a calibration is run (described in section 10 of this method) and an initial demonstration of method capability is performed (described in section 9.2 of this method). Also recovery efficiency for each type of sample must be determined (see section 9.4 of this method).
9.1.2It is permissible to modify this method in order to improve separations or make other improvements, provided that all performance specifications are met. Each time a modification to the method is made it is necessary to repeat the calibration (section 10 of this method), the demonstration of method performance (section 9.2 of this method) and the recovery efficiency for each type of sample (section 9.4 of this method).
9.1.3Ongoing performance should be monitored by running a spiked rubber standard. If this test fails to demonstrate that the analysis is in control, then corrective action must be taken. This method is described in section 9.3 of this method.
9.1.4If new types of samples are being analyzed then recovery efficiency for each new type of sample must be determined. New type includes any change, such as polymer type, physical form or a significant change in the composition of the matrix.
9.2Initial demonstration of method capability to establish the accuracy and precision of the method. This is to be run following the calibration described in section 10 of this method.
9.2.1Prepare a series of identical spiked rubber standards as described in section 9.3 of this method. A sufficient number to determine statistical information on the test should be run. Ten may be a suitable number, depending on the quality control methodology used at the laboratory running the tests. These are run in the same manner as unknown samples (see section 11 of this method).
9.2.2Determine mean and standard deviation for the results. Use these to determine the capability of the method and to calculate suitable control limits for the ongoing performance check which will utilize the same standards.
9.2.3Prepare several additional spiked rubber standards and run 2 each day to determine the suitability of storage of the samples for 24, 48 and 72 hours or longer if longer storage times are desired.
9.3A spiked rubber standard should be run on a regular basis to verify system performance. This would probably be done daily if samples are run daily. This is prepared in the same manner as the calibration standards (section 10.1 of this method), except that only one concentration of toluene and styrene is prepared. Choose concentrations of toluene and styrene that fall in the middle of the range expected in the stripper crumb and then do not change these unless there is a major change in the composition of the unknowns. If it becomes necessary to change the composition of this standard the initial performance demonstration must be repeated with the new standard (section 9.2 of this method).
9.3.1Each day prepare one spiked rubber standard to be run the following day. The dry rubber may be prepared in bulk and stored for any length of time consistent with the shelf life of the product. The addition of water and hydrocarbons must be performed daily and all the steps described under section 10.1 of this method must be followed.
9.3.2Run the spiked rubber standard prepared the previous day. Record the results and plot on an appropriate control chart or other means of determining statistical control.
9.3.3If the results for the standard indicate that the test is out of control then corrective action must be taken. This may include a check on procedures, instrument settings, maintenance or recalibration. Samples may be stored (see section 8.2 of this method) until compliance is demonstrated.
9.4Recovery efficiency must be determined once for each sample type and whenever modifications are made to the method.
9.4.1For each sample type collect 12 samples from the process (section 8.1 of this method). This should be done when the process is operating in a normal manner and residual hydrocarbon levels are in the normal range. Half the vials and caps should be tared, labeled “spiked” and numbered 1 through 6. The other vials are labeled “unspiked” and need not be tared but are also numbered 1 through 6. Immediately on sampling, the vials should be capped to prevent loss of volatiles. Allow all the samples to cool completely to ambient temperature. Reweigh each of the vials labeled “spiked” to determine the weight of wet crumb inside.
9.4.2The dry weight of rubber present in the wet crumb is estimated by multiplying the weight of wet crumb by the fraction of nonvolatiles typical for the sample. If this is not known, an additional quantity of crumb may be sampled, weighed, dried in an oven and reweighed to determine the fraction of volatiles and nonvolatiles prior to starting this procedure.
9.4.3To the vials labeled “spiked” add an amount of a mixture of toluene and styrene that is between 40 and 60 % of the amount expected in the crumb. This is done by removing the cap, adding the mixture by syringe, touching the tip of the needle to the sample in order to remove the drop and then immediately recapping the vials. The mixture is not added through the septum, because a punctured septum may leak and vent vapors as the vial is heated. The weights of toluene and styrene added may be calculated from the volumes of the mixture added, its composition and density, or may be determined by the weight of the vials and caps prior to and after addition. The exact dry weight of rubber present and the concentration of residual toluene and styrene are not known at this time so an exact calculation of the concentration of hydrocarbons is not possible until the test is completed.
9.4.4Place all the vials onto a shaker or tumbler for 24 ±2 hours. This is essential in order for the hydrocarbons to be evenly distributed and completely absorbed into the rubber. If this is not followed the toluene and styrene will be mostly at the surface of the rubber and high results will be obtained.
9.4.5Remove the vials from the shaker and tap them so that all the crumb settles to the bottom of the vials. Allow them to stand for 1 hour prior to analysis to allow any liquid to drain fully to the bottom.
9.4.6Run the spiked and unspiked samples in the normal manner. Record the concentrations of toluene and styrene reported for each pair of spiked and unspiked samples with the same vial number.
9.4.7Open each of the vials labeled “spiked”, remove all the rubber crumb and place it into a tarred drying pan. Place in a 100 deg C oven for two hours, cool and reweigh. Subtract the weight of the tare to give the dry weight of rubber in each spiked vial. Calculate the concentration of toluene and styrene spiked into each vial as percent of dry rubber weight. This will be slightly different for each vial since the weights of dry rubber will be different.
9.4.8For each hydrocarbon calculate the average recovery efficiency (R) using the following equations:
R=R_Σ(Pn)/6 (average of the 6 individual Rn values)
Where:
Rn=(Cns—Cnu) / Sn
Where:
n=vial number
Cns=concentration of compound measured in spiked sample number n.
Cnu=concentration of compound measured in unspiked sample number n.
Sn=theoretical concentration of compound spiked into sample n calculated in step 9.4.7
9.4.9A different R value should be obtained for each compound (styrene and toluene) and for each sample type.
9.4.10A value of R between 0.70 and 1.30 is acceptable.
9.4.11R is used to correct all reported results for each compound by dividing the measured results of each compound by the R for that compound for the same sample type (see section 12.2 of this method.)
10.0Calibration
10.1Calibration standards are prepared by dosing known amounts of the hydrocarbons of interest into vials containing known amounts of rubber and water.
10.1.1Cut a sufficient quantity of dry rubber of the same type as will be analyzed into pieces about the same size as that of the crumb. Place these in a single layer on a piece of aluminum foil or other suitable surface and place into a forced air oven at 100 °C for four hours. This is to remove any residual hydrocarbons that may be present. This step may be performed in advance.
10.1.2Into each of a series of vials add 3.0 g of the dry rubber.
10.1.3Into each vial add 1.0 ml distilled water or an amount that is close to the amount that will be present in the unknowns. The exact amount of water present does not have much effect on the analysis, but it is necessary to have a saturated environment. The water will also aid in the uniform distribution of the spiked hydrocarbons over the surface of the rubber after the vials are placed on the shaker (in step 10.1.5 of this method).
10.1.4Into each vial add varying amounts of toluene and styrene by microliter syringe and cap the vials immediately to prevent loss. The tip of the needle should be carefully touched to the rubber in order to transfer the last drop to the rubber. Toluene and styrene may first be mixed together in suitable proportions and added together if desired. The weights of toluene and styrene added may be calculated from the volumes of the mixture added, its composition and density, or may be determined by the weight of the vials and caps prior to and after addition. Concentrations of added hydrocarbons are calculated as percent of the dry rubber weight. At least 5 standards should be prepared with the amounts of hydrocarbons added being calculated to cover the entire range possible in the unknowns. Retain two samples with no added hydrocarbons as blanks.
10.1.5Place all the vials onto a shaker or tumbler for 24 ±2 hours. This is essential in order for the hydrocarbons to be evenly distributed and completely absorbed into the rubber. If this is not followed the toluene and styrene will be mostly at the surface of the rubber and high results will be obtained.
10.1.6Remove the vials from the shaker and tap them so that all the crumb settles to the bottom of the vials. Allow them to stand for 1 hour prior to analysis to allow any liquid to drain fully to the bottom.
10.2Run the standards and blanks in the same manner as described for unknowns (section 11 of this method), starting with a blank, then in order of increasing hydrocarbon content and ending with the other blank.
10.3Verify that the blanks are sufficiently free from toluene and styrene or any interfering hydrocarbons.
10.3.1It is possible that trace levels may be present even in dry product. If levels are high enough that they will interfere with the calibration then the drying procedure in section 10.1.1 of this method should be reviewed and modified as needed to ensure that suitable standards can be prepared.
10.3.2It is possible that the final blank is contaminated by the previous standard. If this is the case review and modify the sampler parameters as needed to eliminate this problem. If necessary it is possible to run blank samples between regular samples in order to reduce this problem, though it should not be necessary if the sampler is properly set up.
10.4Enter the amounts of toluene and styrene added to each of the samples (as calculated in section 10.1.4 of this method) into the calibration table and perform a calibration utilizing the external standard method of analysis.
10.5At low concentrations the calibration should be close to linear. If a wide range of levels are to be determined it may be desirable to apply a nonlinear calibration to get the best fit.
11.0Procedure
11.1Place the vials in the tray of the headspace sampler. Enter the starting and ending positions through the console of the sampler. For unknown samples each is run in duplicate to minimize the effect of variations in crumb composition. If excessive variation is noted it may be desirable to run more than two of each sample.
11.2Make sure the correct method is loaded on the Chemstation. Turn on the gas flows and light the FID flame.
11.3Start the sequence on the Chemstation. Press the START button on the headspace unit. The samples will be automatically injected after equilibrating for 30 minutes in the oven. As each sample is completed the Chemstation will calculate and print out the results as percent toluene and styrene in the crumb based on the dry weight of rubber.
12.0Data Analysis and Calculations
12.1For each set of duplicate samples calculate the average of the measured concentration of toluene and styrene. If more than two replicates of each sample are run calculate the average over all replicates.
12.2For each sample correct the measured amounts of toluene and styrene using the following equation:
Corrected Result = Cm/R
Where:
Cm = Average measured concentration for that compound.
R = Recovery efficiency for that compound in the same sample type (see section 9.4 of this method)
12.3Report the recovery efficiency (R) and the corrected results of toluene and styrene for each sample.
13.0Method Performance
13.1This method can be very sensitive and reproducible. The actual performance depends largely on the exact nature of the samples being analyzed. Actual performance must be determined by each laboratory for each sample type.
13.2The main source of variation is the actual variation in the composition of non homogeneous crumb in a stripping system and the small sample sizes employed here. It therefore is the responsibility of each laboratory to determine the optimum number of replicates of each sample required to obtain accurate results.
14.0Pollution Prevention
14.1Samples should be kept sealed when possible in order to prevent evaporation of hydrocarbons.
14.2When drying of samples is required it should be done in an oven which vents into a suitable device that can trap the hydrocarbons released.
14.3Dispose of samples as described in section 15.
15.0Waste Management
15.1Excess stripper crumb and water as well as the contents of the used sample vials should be properly disposed of in accordance with local and federal regulations.
15.2Preferably this will be accomplished by having a system of returning unused and spent samples to the process.
16.0References
16.1“HP 7694 Headspace Sampler—Operating and Service Manual”, Hewlett-Packard Company, publication number G1290-90310, June 1993.
Method 313B—The Determination of Residual Hydrocarbon in Solution Polymers by Capillary Gas Chromatography
1.0Scope
1.1This method is applicable to solution polymerized polybutadiene (PBD).
1.2This method quantitatively determines n-hexane in wet crumb polymer at levels from 0.08 to 0.15% by weight.
1.3This method may be extended to the determination of other hydrocarbons in solution produced polymers with proper experimentation and documentation.
2.0Principle of Method
2.1A weighed sample of polymer is dissolved in chloroform and the cement is coagulated with an isopropyl alcohol solution containing a specific amount of alpha-methyl styrene (AMS) as the internal standard. The extract of this coagulation is then injected into a gas chromatograph and separated into individual components. Quantification is achieved by the method of internal standardization.
3.0Definitions
3.1The definitions are included in the text as needed.
4.0Interferences [Reserved]
5.0 Safety
5.1This method may involve hazardous materials, operations, and equipment. This method does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this method to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
6.0Equipment and Supplies
6.1Analytical balance, 160 g capacity, 0.1 mg resolution
6.2Bottles, 2-oz capacity with poly-cap screw lids
6.3Mechanical shaker
6.4Syringe, 10-ul capacity
6.5Syringe, 2.5-ml capacity, with 22 gauge 1.25 inch needle, PP/PE material, disposable
6.6Gas chromatograph, Hewlett-Packard model 5890, or equivalent, configured with FID, split injector packed with silanized glass wool.
6.6.1Establish the following gas chromatographic conditions, and allow the system to thoroughly equilibrate before use.
6.6.2Injector parameters:
Injection technique=Split
Injector split flow=86 ml/min
Injector temperature=225 deg C
6.6.3Oven temperature program:
Initial temperature=40 deg C
Initial time=6 min
Program rate=10 deg C/min
Upper limit temperature=175 deg C
Upper limit interval=10 min
6.6.4Detector parameters:
Detector temperature=300 deg C
Hydrogen flow=30 ml/min
Air flow=350 ml/min
Nitrogen make up=26 ml/min
6.7Gas chromatographic columns: SE-54 (5%-phenyl) (1%-vinyl)-methylpolysiloxane, 15 M×0.53 mm ID with a 1.2 micron film thickness, and a Carbowax 20M (polyethylene glycol), 15 M×0.53 mm ID with a 1.2 micron film thickness.
6.7.1Column assembly: using a 0.53 mm ID butt connector union, join the 15 M×0.53 mm SE-54 column to the 15 M×0.53 mm Carbowax 20M. The SE-54 column will be inserted into the injector and the Carbowax 20M inserted into the detector after they have been joined.
6.7.2Column parameters:
Helium flow=2.8 ml/min
Helium headpressure=2 psig
6.8Centrifuge
6.9Data collection system, Hewlett-Packard Model 3396, or equivalent
6.10Pipet, 25-ml capacity, automatic dispensing, and 2 liter reservoir
6.11Pipet, 2-ml capacity, volumetric delivery, class A
6.12Flasks, 100 and 1000-ml capacity, volumetric, class A
6.13Vial, serum, 50-ml capacity, red rubber septa and crimp ring seals
6.14Sample collection basket fabricated out of wire mesh to allow for drainage
7.0Chemicals and Reagents
CHEMICALS:
7.1alpha-Methyl Styrene, C9H10, 99 % purity, CAS 98-83-9
7.2n-Hexane, C6H14, 99 % purity, CAS 110-54-3
7.3Isopropyl alcohol, C3H8O 99.5 % purity, reagent grade, CAS 67-63-0
7.4Chloroform, CHCl3, 99% min., CAS 67-66-3
REAGENTS:
7.5Internal Standard Stock Solution: 10 mg/25 ml AMS in isopropyl alcohol.
7.5.1Into a 25-ml beaker, weigh 0.4 g of AMS to the nearest 0.1 mg.
7.5.2Quantitatively transfer this AMS into a 1-L volumetric flask. Dilute to the mark with isopropyl alcohol.
7.5.3Transfer this solution to the automatic dispensing pipet reservoir. This will be labeled the AMS STOCK SOLUTION.
7.6n-Hexane Stock Solution: 13mg/2ml hexane in isopropyl alcohol.
7.6.1Into a 100-ml volumetric flask, weigh 0.65 g of n-hexane to the nearest 0.1 mg.
7.6.2Dilute to the mark with isopropyl alcohol. This solution will be labeled the n-HEXANE STOCK SOLUTION.
8.0Sample Collection, Preservation and Storage
8.1A sampling device similar to Figure 1 is used to collect a non-vented crumb rubber sample at a location that is after the stripping operation but before the sample is exposed to the atmosphere.
8.2The crumb rubber is allowed to cool before opening the sampling device and removing the sample.
8.3The sampling device is opened and the crumb rubber sample is collected in the sampling basket.
8.4One pound of crumb rubber sample is placed into a polyethylene bag. The bag is labeled with the time, date and sample location.
8.5The sample should be delivered to the laboratory for testing within one hour of sampling.
8.6Laboratory testing will be done within 3 hours of the sampling time.
8.7No special storage conditions are required unless the storage time exceeds 3 hours in which case refrigeration of the samples is recommended.
9.0Quality Control
9.1For each sample type, 12 samples shall be obtained from the process for the recovery study. Half of the vials and caps shall be tared, labeled “spiked”, and numbered 1 through 6. The other vials shall be labeled “unspiked” and need not be tared, but are also numbered 1 through 6.
9.2Determine the % moisture content of the crumb sample. After determining the % moisture content, the correction factor for calculating the dry crumb weight can be determined by using the equation in section 12.2 of this method.
9.3Run the spiked and unspiked samples in the normal manner. Record the concentrations of the n-hexane content of the mixed hexane reported for each pair of spiked and unspiked samples.
9.4For the recovery study, each sample of crumb shall be dissolved in chloroform containing a known amount of mixed hexane solvent.
9.5For each hydrocarbon, calculate the recovery efficiency (R) using the following equations:
Mr=Ms−Mu
R=Mr/S
Where:
Mu=Measured amount of compound in the unspiked sample
Ms=Measured amount of compound in the spiked sample
Mr=Measured amount of the spiked compound
S=Amount of compound added to the spiked sample
R=Fraction of spiked compound recovered
9.6Normally a value of R between 0.70 and 1.30 is acceptable.
9.7R is used to correct all reported results for each compound by dividing the measured results of each compound by the R for that compound for the same sample type.
10.0Calibration
10.1Using the AMS STOCK SOLUTION equipped with the automatic dispensing pipet (7.5.3 of this method), transfer 25.0 ml of the internal standard solution into an uncapped 50-ml serum vial.
10.2Using a 2.0 ml volumetric pipet, quantitatively transfer 2.0 ml of the n-HEXANE STOCK SOLUTION (7.6.2 of this method) into the 50-ml serum vial and cap. This solution will be labeled the CALIBRATION SOLUTION.
10.3Using the conditions prescribed (6.6 of this method), inject 1 µl of the supernate.
10.4Obtain the peak areas and calculate the response factor as described in the calculations section (12.1 of this method).
11.0Procedure
11.1Determination of Dry Polymer Weight
11.1.1Remove wet crumb from the polyethylene bag and place on paper towels to absorb excess surface moisture.
11.1.2Cut small slices or cubes from the center of the crumb sample to improve sample uniformity and further eliminate surface moisture.
11.1.3A suitable gravimetric measurement should be made on a sample of this wet crumb to determine the correction factor needed to calculate the dry polymer weight.
11.2Determination of n-Hexane in Wet Crumb
11.2.1Remove wet crumb from the polyethylene bag and place on paper towels to absorb excess surface moisture.
11.2.2Cut small slices or cubes from the center of the crumb sample to improve sample uniformity and further eliminate surface moisture.
11.2.3Into a tared 2 oz bottle, weigh 1.5 g of wet polymer to the nearest 0.1 mg.
11.2.4Add 25 ml of chloroform to the 2 oz bottle and cap.
11.2.5Using a mechanical shaker, shake the bottle until the polymer dissolves.
11.2.6Using the autodispensing pipet, add 25.0 ml of the AMS STOCK SOLUTION (7.5.3 of this method) to the dissolved polymer solution and cap.
11.2.7Using a mechanical shaker, shake the bottle for 10 minutes to coagulate the dissolved polymer.
11.2.8Centrifuge the sample for 3 minutes at 2000 rpm.
11.2.9Using the conditions prescribed (6.6 of this method), chromatograph 1 µl of the supernate.
11.2.10Obtain the peak areas and calculate the concentration of the component of interest as described in the calculations (12.2 of this method).
12.0Calculations
12.1Calibration:
RFx=(Wx × Ais) / (Wis × Ax)
Where:
RFx=the relative response factor for n-hexane
Wx=the weight (g) of n-hexane in the CALIBRATION
SOLUTION
Ais=the area of AMS
Wis=the weight (g) of AMS in the CALIBRATION SOLUTION
Ax=the area of n-hexane
12.2Procedure:
12.2.1Correction Factor for calculating dry crumb weight.
F=1—(% moisture / 100)
Where:
F=Correction factor for calculating dry crumb weight
% moisture determined by appropriate method
12.2.2Moisture adjustment for chromatographic determination.
Ws=F × Wc
Where:
Ws=the weight (g) of the dry polymer corrected for moisture
F=Correction factor for calculating dry crumb weight
Wc=the weight (g) of the wet crumb in section 9.6
12.2.3Concentration (ppm) of hexane in the wet crumb.
ppmx=(Ax * RFx * Wis * 10000) / (Ais * Ws)
Where:
ppmx=parts per million of n-hexane in the polymer
Ax=the area of n-hexane
RFx=the relative response factor for n-hexane
Wis=the weight (g) of AMS in the sample solution
Ais=the area of AMS
Ws=the weight (g) of the dry polymer corrected for moisture
13.0Method Performance
13.1Precision for the method was determined at the 0.08% level.
The standard deviation was 0.01 and the percent relative standard deviation (RSD) was 16.3 % with five degrees of freedom.
14.0Waste Generation
14.1Waste generation should be minimized where possible.
15.0Waste Management
15.1Discard liquid chemical waste into the chemical waste drum.
15.2Discard polymer waste into the polymer waste container.
16.0References
16.1This method is based on Goodyear Chemical Division Test Method E-964.
Method 315—Determination of Particulate and Methylene Chloride Extractable Matter (MCEM) From Selected Sources at Primary Aluminum Production Facilities
Note:
This method does not include all of the specifications (e.g., equipment and supplies) and procedures (e.g., sampling and analytical) essential to its performance. Some material is incorporated by reference from other methods in this part. Therefore, to obtain reliable results, persons using this method should have a thorough knowledge of at least the following additional test methods: Method 1, Method 2, Method 3, and Method 5 of 40 CFR part 60, appendix A.
1.0Scope and Application
1.1Analytes. Particulate matter (PM). No CAS number assigned. Methylene chloride extractable matter (MCEM). No CAS number assigned.
1.2Applicability. This method is applicable for the simultaneous determination of PM and MCEM when specified in an applicable regulation. This method was developed by consensus with the Aluminum Association and the U.S. Environmental Protection Agency (EPA) and has limited precision estimates for MCEM; it should have similar precision to Method 5 for PM in 40 CFR part 60, appendix A since the procedures are similar for PM.
1.3Data quality objectives. Adherence to the requirements of this method will enhance the quality of the data obtained from air pollutant sampling methods.
2.0Summary of Method
Particulate matter and MCEM are withdrawn isokinetically from the source. PM is collected on a glass fiber filter maintained at a temperature in the range of 120 ±14 °C (248 ±25 °F) or such other temperature as specified by an applicable subpart of the standards or approved by the Administrator for a particular application. The PM mass, which includes any material that condenses on the probe and is subsequently removed in an acetone rinse or on the filter at or above the filtration temperature, is determined gravimetrically after removal of uncombined water. MCEM is then determined by adding a methylene chloride rinse of the probe and filter holder, extracting the condensable hydrocarbons collected in the impinger water, adding an acetone rinse followed by a methylene chloride rinse of the sampling train components after the filter and before the silica gel impinger, and determining residue gravimetrically after evaporating the solvents.
3.0Definitions [Reserved]
4.0Interferences [Reserved]
5.0Safety
This method may involve hazardous materials, operations, and equipment. This method does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this method to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to performing this test method.
6.0Equipment and Supplies
Note:
Mention of trade names or specific products does not constitute endorsement by the EPA.
6.1Sample collection. The following items are required for sample collection:
6.1.1Sampling train. A schematic of the sampling train used in this method is shown in Figure 5-1, Method 5, 40 CFR part 60, appendix A. Complete construction details are given in APTD-0581 (Reference 2 in section 17.0 of this method); commercial models of this train are also available. For changes from APTD-0581 and for allowable modifications of the train shown in Figure 5-1, Method 5, 40 CFR part 60, appendix A, see the following subsections.
Note:
The operating and maintenance procedures for the sampling train are described in APTD-0576 (Reference 3 in section 17.0 of this method). Since correct usage is important in obtaining valid results, all users should read APTD-0576 and adopt the operating and maintenance procedures outlined in it, unless otherwise specified herein. The use of grease for sealing sampling train components is not recommended because many greases are soluble in methylene chloride. The sampling train consists of the following components:
6.1.1.1Probe nozzle. Glass or glass lined with sharp, tapered leading edge. The angle of taper shall be ≤30 °, and the taper shall be on the outside to preserve a constant internal diameter. The probe nozzle shall be of the button-hook or elbow design, unless otherwise specified by the Administrator. Other materials of construction may be used, subject to the approval of the Administrator. A range of nozzle sizes suitable for isokinetic sampling should be available. Typical nozzle sizes range from 0.32 to 1.27 cm (1/8 to 1/2 in.) inside diameter (ID) in increments of 0.16 cm (1/16 in.). Larger nozzle sizes are also available if higher volume sampling trains are used. Each nozzle shall be calibrated according to the procedures outlined in section 10.0 of this method.
6.1.1.2Probe liner. Borosilicate or quartz glass tubing with a heating system capable of maintaining a probe gas temperature at the exit end during sampling of 120 ±14 °C (248±25 °F), or such other temperature as specified by an applicable subpart of the standards or approved by the Administrator for a particular application. Because the actual temperature at the outlet of the probe is not usually monitored during sampling, probes constructed according to APTD-0581 and using the calibration curves of APTD-0576 (or calibrated according to the procedure outlined in APTD-0576) will be considered acceptable. Either borosilicate or quartz glass probe liners may be used for stack temperatures up to about 480 °C (900 °F); quartz liners shall be used for temperatures between 480 and 900 °C (900 and 1,650 °F). Both types of liners may be used at higher temperatures than specified for short periods of time, subject to the approval of the Administrator. The softening temperature for borosilicate glass is 820 °C (1,500 °F) and for quartz glass it is 1,500 °C (2,700 °F).
6.1.1.3Pitot tube. Type S, as described in section 6.1 of Method 2, 40 CFR part 60, appendix A, or other device approved by the Administrator. The pitot tube shall be attached to the probe (as shown in Figure 5-1 of Method 5, 40 CFR part 60, appendix A) to allow constant monitoring of the stack gas velocity. The impact (high pressure) opening plane of the pitot tube shall be even with or above the nozzle entry plane (see Method 2, Figure 2-6b, 40 CFR part 60, appendix A) during sampling. The Type S pitot tube assembly shall have a known coefficient, determined as outlined in section 10.0 of Method 2, 40 CFR part 60, appendix A.
6.1.1.4Differential pressure gauge. Inclined manometer or equivalent device (two), as described in section 6.2 of Method 2, 40 CFR part 60, appendix A. One manometer shall be used for velocity head (Dp) readings, and the other, for orifice differential pressure readings.
6.1.1.5Filter holder. Borosilicate glass, with a glass frit filter support and a silicone rubber gasket. The holder design shall provide a positive seal against leakage from the outside or around the filter. The holder shall be attached immediately at the outlet of the probe (or cyclone, if used).
6.1.1.6Filter heating system. Any heating system capable of maintaining a temperature around the filter holder of 120 ±14 °C (248 ±25 °F) during sampling, or such other temperature as specified by an applicable subpart of the standards or approved by the Administrator for a particular application. Alternatively, the tester may opt to operate the equipment at a temperature lower than that specified. A temperature gauge capable of measuring temperature to within 3 °C (5.4 °F) shall be installed so that the temperature around the filter holder can be regulated and monitored during sampling. Heating systems other than the one shown in APTD-0581 may be used.
6.1.1.7Temperature sensor. A temperature sensor capable of measuring temperature to within ±3 °C (5.4 °F) shall be installed so that the sensing tip of the temperature sensor is in direct contact with the sample gas, and the temperature around the filter holder can be regulated and monitored during sampling.
6.1.1.8Condenser. The following system shall be used to determine the stack gas moisture content: four glass impingers connected in series with leak-free ground glass fittings. The first, third, and fourth impingers shall be of the Greenburg-Smith design, modified by replacing the tip with a 1.3 cm (1/2 in.) ID glass tube extending to about 1.3 cm (1/2 in.) from the bottom of the flask. The second impinger shall be of the Greenburg-Smith design with the standard tip. The first and second impingers shall contain known quantities of water (section 8.3.1 of this method), the third shall be empty, and the fourth shall contain a known weight of silica gel or equivalent desiccant. A temperature sensor capable of measuring temperature to within 1 °C (2 °F) shall be placed at the outlet of the fourth impinger for monitoring.
6.1.1.9Metering system. Vacuum gauge, leak-free pump, temperature sensors capable of measuring temperature to within 3 °C (5.4 °F), dry gas meter (DGM) capable of measuring volume to within 2 percent, and related equipment, as shown in Figure 5-1 of Method 5, 40 CFR part 60, appendix A. Other metering systems capable of maintaining sampling rates within 10 percent of isokinetic and of determining sample volumes to within 2 percent may be used, subject to the approval of the Administrator. When the metering system is used in conjunction with a pitot tube, the system shall allow periodic checks of isokinetic rates.
6.1.1.10Sampling trains using metering systems designed for higher flow rates than that described in APTD-0581 or APTD-0576 may be used provided that the specifications of this method are met.
6.1.2Barometer. Mercury, aneroid, or other barometer capable of measuring atmospheric pressure to within 2.5 mm (0.1 in.) Hg.
Note:
The barometric reading may be obtained from a nearby National Weather Service station. In this case, the station value (which is the absolute barometric pressure) shall be requested and an adjustment for elevation differences between the weather station and sampling point shall be made at a rate of minus 2.5 mm (0.1 in) Hg per 30 m (100 ft) elevation increase or plus 2.5 mm (0.1 in) Hg per 30 m (100 ft) elevation decrease.
6.1.3Gas density determination equipment. Temperature sensor and pressure gauge, as described in sections 6.3 and 6.4 of Method 2, 40 CFR part 60, appendix A, and gas analyzer, if necessary, as described in Method 3, 40 CFR part 60, appendix A. The temperature sensor shall, preferably, be permanently attached to the pitot tube or sampling probe in a fixed configuration, such that the tip of the sensor extends beyond the leading edge of the probe sheath and does not touch any metal. Alternatively, the sensor may be attached just prior to use in the field. Note, however, that if the temperature sensor is attached in the field, the sensor must be placed in an interference-free arrangement with respect to the Type S pitot tube openings (see Method 2, Figure 2-4, 40 CFR part 60, appendix A). As a second alternative, if a difference of not more than 1 percent in the average velocity measurement is to be introduced, the temperature sensor need not be attached to the probe or pitot tube. (This alternative is subject to the approval of the Administrator.)
6.2Sample recovery. The following items are required for sample recovery:
6.2.1Probe-liner and probe-nozzle brushes. Nylon or Teflon ® bristle brushes with stainless steel wire handles. The probe brush shall have extensions (at least as long as the probe) constructed of stainless steel, nylon, Teflon ®, or similarly inert material. The brushes shall be properly sized and shaped to brush out the probe liner and nozzle.
6.2.2Wash bottles. Glass wash bottles are recommended. Polyethylene or tetrafluoroethylene (TFE) wash bottles may be used, but they may introduce a positive bias due to contamination from the bottle. It is recommended that acetone not be stored in polyethylene or TFE bottles for longer than a month.
6.2.3Glass sample storage containers. Chemically resistant, borosilicate glass bottles, for acetone and methylene chloride washes and impinger water, 500 ml or 1,000 ml. Screw-cap liners shall either be rubber-backed Teflon ® or shall be constructed so as to be leak-free and resistant to chemical attack by acetone or methylene chloride. (Narrow-mouth glass bottles have been found to be less prone to leakage.) Alternatively, polyethylene bottles may be used.
6.2.4Petri dishes. For filter samples, glass, unless otherwise specified by the Administrator.
6.2.5Graduated cylinder and/or balance. To measure condensed water, acetone wash and methylene chloride wash used during field recovery of the samples, to within 1 ml or 1 g. Graduated cylinders shall have subdivisions no greater than 2 ml. Most laboratory balances are capable of weighing to the nearest 0.5 g or less. Any such balance is suitable for use here and in section 6.3.4 of this method.
6.2.6Plastic storage containers. Air-tight containers to store silica gel.
6.2.7Funnel and rubber policeman. To aid in transfer of silica gel to container; not necessary if silica gel is weighed in the field.
6.2.8Funnel. Glass or polyethylene, to aid in sample recovery.
6.3Sample analysis. The following equipment is required for sample analysis:
6.3.1Glass or Teflon ® weighing dishes.
6.3.2Desiccator. It is recommended that fresh desiccant be used to minimize the chance for positive bias due to absorption of organic material during drying.
6.3.3Analytical balance. To measure to within 0.l mg.
6.3.4Balance. To measure to within 0.5 g.
6.3.5Beakers. 250 ml.
6.3.6Hygrometer. To measure the relative humidity of the laboratory environment.
6.3.7Temperature sensor. To measure the temperature of the laboratory environment.
6.3.8Buchner fritted funnel. 30 ml size, fine (<50 micron)-porosity fritted glass.
6.3.9Pressure filtration apparatus.
6.3.10Aluminum dish. Flat bottom, smooth sides, and flanged top, 18 mm deep and with an inside diameter of approximately 60 mm.
7.0Reagents and Standards
7.lSample collection. The following reagents are required for sample collection:
7.1.1Filters. Glass fiber filters, without organic binder, exhibiting at least 99.95 percent efficiency (<0.05 percent penetration) on 0.3 micron dioctyl phthalate smoke particles. The filter efficiency test shall be conducted in accordance with ASTM Method D 2986-95A (incorporated by reference in § 63.841 of this part). Test data from the supplier's quality control program are sufficient for this purpose. In sources containing S02 or S03, the filter material must be of a type that is unreactive to S02 or S03. Reference 10 in section 17.0 of this method may be used to select the appropriate filter.
7.1.2Silica gel. Indicating type, 6 to l6 mesh. If previously used, dry at l75 °C (350 °F) for 2 hours. New silica gel may be used as received. Alternatively, other types of desiccants (equivalent or better) may be used, subject to the approval of the Administrator.
7.1.3Water. When analysis of the material caught in the impingers is required, deionized distilled water shall be used. Run blanks prior to field use to eliminate a high blank on test samples.
7.1.4Crushed ice.
7.1.5Stopcock grease. Acetone-insoluble, heat-stable silicone grease. This is not necessary if screw-on connectors with Teflon” sleeves, or similar, are used. Alternatively, other types of stopcock grease may be used, subject to the approval of the Administrator. [Caution: Many stopcock greases are methylene chloride-soluble. Use sparingly and carefully remove prior to recovery to prevent contamination of the MCEM analysis.]
7.2Sample recovery. The following reagents are required for sample recovery:
7.2.1Acetone. Acetone with blank values < 1 ppm, by weight residue, is required. Acetone blanks may be run prior to field use, and only acetone with low blank values may be used. In no case shall a blank value of greater than 1E-06 of the weight of acetone used be subtracted from the sample weight.
Note:
This is more restrictive than Method 5, 40 CFR part 60, appendix A. At least one vendor (Supelco Incorporated located in Bellefonte, Pennsylvania) lists <1 mg/l as residue for its Environmental Analysis Solvents.
7.2.2Methylene chloride. Methylene chloride with a blank value <1.5 ppm, by weight, residue. Methylene chloride blanks may be run prior to field use, and only methylene chloride with low blank values may be used. In no case shall a blank value of greater than 1.6E-06 of the weight of methylene chloride used be subtracted from the sample weight.
Note:
A least one vendor quotes <1 mg/l for Environmental Analysis Solvents-grade methylene chloride.
7.3Sample analysis. The following reagents are required for sample analysis:
7.3.lAcetone. Same as in section 7.2.1 of this method.
7.3.2Desiccant. Anhydrous calcium sulfate, indicating type. Alternatively, other types of desiccants may be used, subject to the approval of the Administrator.
7.3.3Methylene chloride. Same as in section 7.2.2 of this method.
8.0Sample Collection, Preservation, Storage, and Transport
Note:
The complexity of this method is such that, in order to obtain reliable results, testers should be trained and experienced with the test procedures.
8.11Pretest preparation. It is suggested that sampling equipment be maintained according to the procedures described in APTD-0576.
8.1.1Weigh several 200 g to 300 g portions of silica gel in airtight containers to the nearest 0.5 g. Record on each container the total weight of the silica gel plus container. As an alternative, the silica gel need not be preweighed but may be weighed directly in its impinger or sampling holder just prior to train assembly.
8.1.2A batch of glass fiber filters, no more than 50 at a time, should placed in a soxhlet extraction apparatus and extracted using methylene chloride for at least 16 hours. After extraction, check filters visually against light for irregularities, flaws, or pinhole leaks. Label the shipping containers (glass or plastic petri dishes), and keep the filters in these containers at all times except during sampling and weighing.
8.1.3Desiccate the filters at 20 ±5.6 °C (68 ±10 °F) and ambient pressure for at least 24 hours and weigh at intervals of at least 6 hours to a constant weight, i.e., <0.5 mg change from previous weighing; record results to the nearest 0.1 mg. During each weighing the filter must not be exposed to the laboratory atmosphere for longer than 2 minutes and a relative humidity above 50 percent. Alternatively (unless otherwise specified by the Administrator), the filters may be oven-dried at 104 °C (220 °F) for 2 to 3 hours, desiccated for 2 hours, and weighed. Procedures other than those described, which account for relative humidity effects, may be used, subject to the approval of the Administrator.
8.2Preliminary determinations.
8.2.1Select the sampling site and the minimum number of sampling points according to Method 1, 40 CFR part 60, appendix A or as specified by the Administrator. Determine the stack pressure, temperature, and the range of velocity heads using Method 2, 40 CFR part 60, appendix A; it is recommended that a leak check of the pitot lines (see section 8.1 of Method 2, 40 CFR part 60, appendix A) be performed. Determine the moisture content using Approximation Method 4 (section 1.2 of Method 4, 40 CFR part 60, appendix A) or its alternatives to make isokinetic sampling rate settings. Determine the stack gas dry molecular weight, as described in section 8.6 of Method 2, 40 CFR part 60, appendix A; if integrated Method 3 sampling is used for molecular weight determination, the integrated bag sample shall be taken simultaneously with, and for the same total length of time as, the particulate sample run.
8.2.2Select a nozzle size based on the range of velocity heads such that it is not necessary to change the nozzle size in order to maintain isokinetic sampling rates. During the run, do not change the nozzle size. Ensure that the proper differential pressure gauge is chosen for the range of velocity heads encountered (see section 8.2 of Method 2, 40 CFR part 60, appendix A).
8.2.3Select a suitable probe liner and probe length such that all traverse points can be sampled. For large stacks, consider sampling from opposite sides of the stack to reduce the required probe length.
8.2.4Select a total sampling time greater than or equal to the minimum total sampling time specified in the test procedures for the specific industry such that: (1) The sampling time per point is not less than 2 minutes (or some greater time interval as specified by the Administrator); and (2) the sample volume taken (corrected to standard conditions) will exceed the required minimum total gas sample volume. The latter is based on an approximate average sampling rate.
8.2.5The sampling time at each point shall be the same. It is recommended that the number of minutes sampled at each point be an integer or an integer plus one-half minute, in order to eliminate timekeeping errors.
8.2.6In some circumstances (e.g., batch cycles), it may be necessary to sample for shorter times at the traverse points and to obtain smaller gas sample volumes. In these cases, the Administrator's approval must first be obtained.
8.3Preparation of sampling train.
8.3.1During preparation and assembly of the sampling train, keep all openings where contamination can occur covered until just prior to assembly or until sampling is about to begin. Place l00 ml of water in each of the first two impingers, leave the third impinger empty, and transfer approximately 200 to 300 g of preweighed silica gel from its container to the fourth impinger. More silica gel may be used, but care should be taken to ensure that it is not entrained and carried out from the impinger during sampling. Place the container in a clean place for later use in the sample recovery. Alternatively, the weight of the silica gel plus impinger may be determined to the nearest 0.5 g and recorded.
8.3.2Using a tweezer or clean disposable surgical gloves, place a labeled (identified) and weighed filter in the filter holder. Be sure that the filter is properly centered and the gasket properly placed so as to prevent the sample gas stream from circumventing the filter. Check the filter for tears after assembly is completed.
8.3.3When glass liners are used, install the selected nozzle using a Viton A 0-ring when stack temperatures are less than 260 °C (500 °F) and an asbestos string gasket when temperatures are higher. See APTD-0576 for details. Mark the probe with heat-resistant tape or by some other method to denote the proper distance into the stack or duct for each sampling point.
8.3.4Set up the train as in Figure 5-1 of Method 5, 40 CFR part 60, appendix A, using (if necessary) a very light coat of silicone grease on all ground glass joints, greasing only the outer portion (see APTD-0576) to avoid possibility of contamination by the silicone grease. Subject to the approval of the Administrator, a glass cyclone may be used between the probe and filter holder when the total particulate catch is expected to exceed 100 mg or when water droplets are present in the stack gas.
8.3.5Place crushed ice around the impingers.
8.4Leak-check procedures.
8.4.1Leak check of metering system shown in Figure 5-1 of Method 5, 40 CFR part 60, appendix A. That portion of the sampling train from the pump to the orifice meter should be leak-checked prior to initial use and after each shipment. Leakage after the pump will result in less volume being recorded than is actually sampled. The following procedure is suggested (see Figure 5-2 of Method 5, 40 CFR part 60, appendix A): Close the main valve on the meter box. Insert a one-hole rubber stopper with rubber tubing attached into the orifice exhaust pipe. Disconnect and vent the low side of the orifice manometer. Close off the low side orifice tap. Pressurize the system to 13 to 18 cm (5 to 7 in.) water column by blowing into the rubber tubing. Pinch off the tubing, and observe the manometer for 1 minute. A loss of pressure on the manometer indicates a leak in the meter box; leaks, if present, must be corrected.
8.4.2Pretest leak check. A pretest leak-check is recommended but not required. If the pretest leak-check is conducted, the following procedure should be used.
8.4.2.1After the sampling train has been assembled, turn on and set the filter and probe heating systems to the desired operating temperatures. Allow time for the temperatures to stabilize. If a Viton A 0-ring or other leak-free connection is used in assembling the probe nozzle to the probe liner, leak-check the train at the sampling site by plugging the nozzle and pulling a 380 mm (15 in.) Hg vacuum.
Note:
A lower vacuum may be used, provided that it is not exceeded during the test.
8.4.2.2If an asbestos string is used, do not connect the probe to the train during the leak check. Instead, leak-check the train by first plugging the inlet to the filter holder (cyclone, if applicable) and pulling a 380 mm (15 in.) Hg vacuum. (See NOTE in section 8.4.2.1 of this method). Then connect the probe to the train and perform the leak check at approximately 25 mm (1 in.) Hg vacuum; alternatively, the probe may be leak-checked with the rest of the sampling train, in one step, at 380 mm (15 in.) Hg vacuum. Leakage rates in excess of 4 percent of the average sampling rate or 0.00057 m3/min (0.02 cfm), whichever is less, are unacceptable.
8.4.2.3The following leak check instructions for the sampling train described in APTD-0576 and APTD-058l may be helpful. Start the pump with the bypass valve fully open and the coarse adjust valve completely closed. Partially open the coarse adjust valve and slowly close the bypass valve until the desired vacuum is reached. Do not reverse the direction of the bypass valve, as this will cause water to back up into the filter holder. If the desired vacuum is exceeded, either leak-check at this higher vacuum or end the leak check as shown below and start over.
8.4.2.4When the leak check is completed, first slowly remove the plug from the inlet to the probe, filter holder, or cyclone (if applicable) and immediately turn off the vacuum pump. This prevents the water in the impingers from being forced backward into the filter holder and the silica gel from being entrained backward into the third impinger.
8.4.3Leak checks during sample run. If, during the sampling run, a component (e.g., filter assembly or impinger) change becomes necessary, a leak check shall be conducted immediately before the change is made. The leak check shall be done according to the procedure outlined in section 8.4.2 of this method, except that it shall be done at a vacuum equal to or greater than the maximum value recorded up to that point in the test. If the leakage rate is found to be no greater than 0.00057 m3/min (0.02 cfm) or 4 percent of the average sampling rate (whichever is less), the results are acceptable, and no correction will need to be applied to the total volume of dry gas metered; if, however, a higher leakage rate is obtained, either record the leakage rate and plan to correct the sample volume as shown in section 12.3 of this method or void the sample run.
Note:
Immediately after component changes, leak checks are optional; if such leak checks are done, the procedure outlined in section 8.4.2 of this method should be used.
8.4.4Post-test leak check. A leak check is mandatory at the conclusion of each sampling run. The leak check shall be performed in accordance with the procedures outlined in section 8.4.2 of this method, except that it shall be conducted at a vacuum equal to or greater than the maximum value reached during the sampling run. If the leakage rate is found to be no greater than 0.00057 m3/min (0.02 cfm) or 4 percent of the average sampling rate (whichever is less), the results are acceptable, and no correction need be applied to the total volume of dry gas metered. If, however, a higher leakage rate is obtained, either record the leakage rate and correct the sample volume, as shown in section 12.4 of this method, or void the sampling run.
8.5Sampling train operation. During the sampling run, maintain an isokinetic sampling rate (within l0 percent of true isokinetic unless otherwise specified by the Administrator) and a temperature around the filter of 120 14 °C (248 25 °F), or such other temperature as specified by an applicable subpart of the standards or approved by the Administrator.
8.5.1For each run, record the data required on a data sheet such as the one shown in Figure 5-2 of Method 5, 40 CFR part 60, appendix A. Be sure to record the initial reading. Record the DGM readings at the beginning and end of each sampling time increment, when changes in flow rates are made, before and after each leak-check, and when sampling is halted. Take other readings indicated by Figure 5-2 of Method 5, 40 CFR part 60, appendix A at least once at each sample point during each time increment and additional readings when significant changes (20 percent variation in velocity head readings) necessitate additional adjustments in flow rate. Level and zero the manometer. Because the manometer level and zero may drift due to vibrations and temperature changes, make periodic checks during the traverse.
8.5.2Clean the portholes prior to the test run to minimize the chance of sampling deposited material. To begin sampling, remove the nozzle cap and verify that the filter and probe heating systems are up to temperature and that the pitot tube and probe are properly positioned. Position the nozzle at the first traverse point with the tip pointing directly into the gas stream. Immediately start the pump and adjust the flow to isokinetic conditions. Nomographs are available, which aid in the rapid adjustment of the isokinetic sampling rate without excessive computations. These nomographs are designed for use when the Type S pitot tube coefficient (Cp) is 0.85 # 0.02 and the stack gas equivalent density (dry molecular weight) is 29 ±4. APTD-0576 details the procedure for using the nomographs. If Cp and Md are outside the above-stated ranges, do not use the nomographs unless appropriate steps (see Reference 7 in section 17.0 of this method) are taken to compensate for the deviations.
8.5.3When the stack is under significant negative pressure (height of impinger stem), close the coarse adjust valve before inserting the probe into the stack to prevent water from backing into the filter holder. If necessary, the pump may be turned on with the coarse adjust valve closed.
8.5.4When the probe is in position, block off the openings around the probe and porthole to prevent unrepresentative dilution of the gas stream.
8.5.5Traverse the stack cross-section, as required by Method 1, 40 CFR part 60, appendix A or as specified by the Administrator, being careful not to bump the probe nozzle into the stack walls when sampling near the walls or when removing or inserting the probe through the portholes; this minimizes the chance of extracting deposited material.
8.5.6During the test run, make periodic adjustments to keep the temperature around the filter holder at the proper level; add more ice and, if necessary, salt to maintain a temperature of less than 20 °C (68 °F) at the condenser/silica gel outlet. Also, periodically check the level and zero of the manometer.
8.5.7If the pressure drop across the filter becomes too high, making isokinetic sampling difficult to maintain, the filter may be replaced in the midst of the sample run. It is recommended that another complete filter assembly be used rather than attempting to change the filter itself. Before a new filter assembly is installed, conduct a leak check (see section 8.4.3 of this method). The total PM weight shall include the summation of the filter assembly catches.
8.5.8A single train shall be used for the entire sample run, except in cases where simultaneous sampling is required in two or more separate ducts or at two or more different locations within the same duct, or in cases where equipment failure necessitates a change of trains. In all other situations, the use of two or more trains will be subject to the approval of the Administrator.
Note:
When two or more trains are used, separate analyses of the front-half and (if applicable) impinger catches from each train shall be performed, unless identical nozzle sizes were used in all trains, in which case the front-half catches from the individual trains may be combined (as may the impinger catches) and one analysis of the front-half catch and one analysis of the impinger catch may be performed.
8.5.9At the end of the sample run, turn off the coarse adjust valve, remove the probe and nozzle from the stack, turn off the pump, record the final DGM reading, and then conduct a post-test leak check, as outlined in section 8.4.4 of this method. Also leak-check the pitot lines as described in section 8.1 of Method 2, 40 CFR part 60, appendix A. The lines must pass this leak check in order to validate the velocity head data.
8.6Calculation of percent isokinetic. Calculate percent isokinetic (see Calculations, section 12.12 of this method) to determine whether a run was valid or another test run should be made. If there was difficulty in maintaining isokinetic rates because of source conditions, consult the Administrator for possible variance on the isokinetic rates.
8.7 Sample recovery.
8.7.1Proper cleanup procedure begins as soon as the probe is removed from the stack at the end of the sampling period. Allow the probe to cool.
8.7.2When the probe can be safely handled, wipe off all external PM near the tip of the probe nozzle and place a cap over it to prevent losing or gaining PM. Do not cap off the probe tip tightly while the sampling train is cooling down. This would create a vacuum in the filter holder, thus drawing water from the impingers into the filter holder.
8.7.3Before moving the sample train to the cleanup site, remove the probe from the sample train, wipe off the silicone grease, and cap the open outlet of the probe. Be careful not to lose any condensate that might be present. Wipe off the silicone grease from the filter inlet where the probe was fastened and cap it. Remove the umbilical cord from the last impinger and cap the impinger. If a flexible line is used between the first impinger or condenser and the filter holder, disconnect the line at the filter holder and let any condensed water or liquid drain into the impingers or condenser. After wiping off the silicone grease, cap off the filter holder outlet and impinger inlet. Ground-glass stoppers, plastic caps, or serum caps may be used to close these openings.
8.7.4Transfer the probe and filter-impinger assembly to the cleanup area. This area should be clean and protected from the wind so that the chances of contaminating or losing the sample will be minimized.
8.7.5Save a portion of the acetone and methylene chloride used for cleanup as blanks. Take 200 ml of each solvent directly from the wash bottle being used and place it in glass sample containers labeled “acetone blank” and “methylene chloride blank,” respectively.
8.7.6Inspect the train prior to and during disassembly and note any abnormal conditions. Treat the samples as follows:
8.7.6.1Container No. 1. Carefully remove the filter from the filter holder, and place it in its identified petri dish container. Use a pair of tweezers and/or clean disposable surgical gloves to handle the filter. If it is necessary to fold the filter, do so such that the PM cake is inside the fold. Using a dry nylon bristle brush and/or a sharp-edged blade, carefully transfer to the petri dish any PM and/or filter fibers that adhere to the filter holder gasket. Seal the container.
8.7.6.2Container No. 2. Taking care to see that dust on the outside of the probe or other exterior surfaces does not get into the sample, quantitatively recover PM or any condensate from the probe nozzle, probe fitting, probe liner, and front half of the filter holder by washing these components with acetone and placing the wash in a glass container. Perform the acetone rinse as follows:
8.7.6.2.1Carefully remove the probe nozzle and clean the inside surface by rinsing with acetone from a wash bottle and brushing with a nylon bristle brush. Brush until the acetone rinse shows no visible particles, after which make a final rinse of the inside surface with acetone.
8.7.6.2.2Brush and rinse the inside parts of the Swagelok fitting with acetone in a similar way until no visible particles remain.
8.7.6.2.3Rinse the probe liner with acetone by tilting and rotating the probe while squirting acetone into its upper end so that all inside surfaces are wetted with acetone. Let the acetone drain from the lower end into the sample container. A funnel (glass or polyethylene) may be used to aid in transferring liquid washes to the container. Follow the acetone rinse with a probe brush. Hold the probe in an inclined position, squirt acetone into the upper end as the probe brush is being pushed with a twisting action through the probe, hold a sample container under the lower end of the probe, and catch any acetone and PM that is brushed from the probe. Run the brush through the probe three times or more until no visible PM is carried out with the acetone or until none remains in the probe liner on visual inspection. With stainless steel or other metal probes, run the brush through in the above-described manner at least six times, since metal probes have small crevices in which PM can be entrapped. Rinse the brush with acetone and quantitatively collect these washings in the sample container. After the brushing, make a final acetone rinse of the probe as described above.
8.7.6.2.4It is recommended that two people clean the probe to minimize sample losses. Between sampling runs, keep brushes clean and protected from contamination.
8.7.6.2.5After ensuring that all joints have been wiped clean of silicone grease, clean the inside of the front half of the filter holder by rubbing the surfaces with a nylon bristle brush and rinsing with acetone. Rinse each surface three times or more if needed to remove visible particulate. Make a final rinse of the brush and filter holder. Carefully rinse out the glass cyclone also (if applicable).
8.7.6.2.6After rinsing the nozzle, probe, and front half of the filter holder with acetone, repeat the entire procedure with methylene chloride and save in a separate No. 2M container.
8.7.6.2.7After acetone and methylene chloride washings and PM have been collected in the proper sample containers, tighten the lid on the sample containers so that acetone and methylene chloride will not leak out when it is shipped to the laboratory. Mark the height of the fluid level to determine whether leakage occurs during transport. Label each container to identify clearly its contents.
8.7.6.3Container No. 3. Note the color of the indicating silica gel to determine whether it has been completely spent, and make a notation of its condition. Transfer the silica gel from the fourth impinger to its original container and seal the container. A funnel may make it easier to pour the silica gel without spilling. A rubber policeman may be used as an aid in removing the silica gel from the impinger. It is not necessary to remove the small amount of dust particles that may adhere to the impinger wall and are difficult to remove. Since the gain in weight is to be used for moisture calculations, do not use any water or other liquids to transfer the silica gel. If a balance is available in the field, follow the procedure for Container No. 3 in section 11.2.3 of this method.
8.7.6.4Impinger water. Treat the impingers as follows:
8.7.6.4.1Make a notation of any color or film in the liquid catch. Measure the liquid that is in the first three impingers to within 1 ml by using a graduated cylinder or by weighing it to within 0.5 g by using a balance (if one is available). Record the volume or weight of liquid present. This information is required to calculate the moisture content of the effluent gas.
8.7.6.4.2Following the determination of the volume of liquid present, rinse the back half of the train with water, add it to the impinger catch, and store it in a container labeled 3W (water).
8.7.6.4.3Following the water rinse, rinse the back half of the train with acetone to remove the excess water to enhance subsequent organic recovery with methylene chloride and quantitatively recover to a container labeled 3S (solvent) followed by at least three sequential rinsings with aliquots of methylene chloride. Quantitatively recover to the same container labeled 3S. Record separately the amount of both acetone and methylene chloride used to the nearest 1 ml or 0.5g.
Note:
Because the subsequent analytical finish is gravimetric, it is okay to recover both solvents to the same container. This would not be recommended if other analytical finishes were required.
8.8Sample transport. Whenever possible, containers should be shipped in such a way that they remain upright at all times.
9.0Quality Control
9.1Miscellaneous quality control measures.
Section Quality control measure Effect
8.4, 10.1-10.6 Sampling and equipment leak check and calibration Ensure accurate measurement of stack gas flow rate, sample volume.
9.2Volume metering system checks. The following quality control procedures are suggested to check the volume metering system calibration values at the field test site prior to sample collection. These procedures are optional.
9.2.1Meter orifice check. Using the calibration data obtained during the calibration procedure described in section 10.3 of this method, determine the ΔHa for the metering system orifice. The ΔHa is the orifice pressure differential in units of in. H20 that correlates to 0.75 cfm of air at 528 °R and 29.92 in. Hg. The ΔHa is calculated as follows:
Where
0.0319 = (0.0567 in. Hg/ °R)(0.75 cfm)2;
ΔH = Average pressure differential across the orifice meter, in. H20;
Tm = Absolute average DGM temperature, °R;
Θ = Total sampling time, min;
Pbar = Barometric pressure, in. Hg;
Y = DGM calibration factor, dimensionless;
Vm = Volume of gas sample as measured by DGM, dcf.
9.2.1.1Before beginning the field test (a set of three runs usually constitutes a field test), operate the metering system (i.e., pump, volume meter, and orifice) at the ΔHa pressure differential for 10 minutes. Record the volume collected, the DGM temperature, and the barometric pressure. Calculate a DGM calibration check value, Yc, as follows:
Where
Yc = DGM calibration check value, dimensionless;
10 = Run time, min.
9.2.1.2Compare the Yc value with the dry gas meter calibration factor Y to determine that: 0.97 Y < Yc < 1.03Y. If the Yc value is not within this range, the volume metering system should be investigated before beginning the test.
9.2.2Calibrated critical orifice. A calibrated critical orifice, calibrated against a wet test meter or spirometer and designed to be inserted at the inlet of the sampling meter box, may be used as a quality control check by following the procedure of section 16.2 of this method.
10.0 Calibration and Standardization
Note:
Maintain a laboratory log of all calibrations.
10.1Probe nozzle. Probe nozzles shall be calibrated before their initial use in the field. Using a micrometer, measure the ID of the nozzle to the nearest 0.025 mm (0.001 in.). Make three separate measurements using different diameters each time, and obtain the average of the measurements. The difference between the high and low numbers shall not exceed 0.1 mm (0.004 in.). When nozzles become nicked, dented, or corroded, they shall be reshaped, sharpened, and recalibrated before use. Each nozzle shall be permanently and uniquely identified.
10.2Pitot tube assembly. The Type S pitot tube assembly shall be calibrated according to the procedure outlined in section 10.1 of Method 2, 40 CFR part 60, appendix A.
10.3Metering system.
10.3.1Calibration prior to use. Before its initial use in the field, the metering system shall be calibrated as follows: Connect the metering system inlet to the outlet of a wet test meter that is accurate to within 1 percent. Refer to Figure 5-5 of Method 5, 40 CFR part 60, appendix A. The wet test meter should have a capacity of 30 liters/revolution (1 ft3/rev). A spirometer of 400 liters (14 ft3) or more capacity, or equivalent, may be used for this calibration, although a wet test meter is usually more practical. The wet test meter should be periodically calibrated with a spirometer or a liquid displacement meter to ensure the accuracy of the wet test meter. Spirometers or wet test meters of other sizes may be used, provided that the specified accuracies of the procedure are maintained. Run the metering system pump for about 15 minutes with the orifice manometer indicating a median reading, as expected in field use, to allow the pump to warm up and to permit the interior surface of the wet test meter to be thoroughly wetted. Then, at each of a minimum of three orifice manometer settings, pass an exact quantity of gas through the wet test meter and note the gas volume indicated by the DGM. Also note the barometric pressure and the temperatures of the wet test meter, the inlet of the DGM, and the outlet of the DGM. Select the highest and lowest orifice settings to bracket the expected field operating range of the orifice. Use a minimum volume of 0.15 m3 (5 cf) at all orifice settings. Record all the data on a form similar to Figure 5-6 of Method 5, 40 CFR part 60, appendix A, and calculate Y (the DGM calibration factor) and ΔHa (the orifice calibration factor) at each orifice setting, as shown on Figure 5-6 of Method 5, 40 CFR part 60, appendix A. Allowable tolerances for individual Y and ΔHa values are given in Figure 5-6 of Method 5, 40 CFR part 60, appendix A. Use the average of the Y values in the calculations in section 12 of this method.
10.3.1.1Before calibrating the metering system, it is suggested that a leak check be conducted. For metering systems having diaphragm pumps, the normal leak check procedure will not detect leakages within the pump. For these cases the following leak check procedure is suggested: make a 10-minute calibration run at 0.00057 m3/min (0.02 cfm); at the end of the run, take the difference of the measured wet test meter and DGM volumes; divide the difference by 10 to get the leak rate. The leak rate should not exceed 0.00057 m3/min (0.02 cfm).
10.3.2Calibration after use. After each field use, the calibration of the metering system shall be checked by performing three calibration runs at a single, intermediate orifice setting (based on the previous field test) with the vacuum set at the maximum value reached during the test series. To adjust the vacuum, insert a valve between the wet test meter and the inlet of the metering system. Calculate the average value of the DGM calibration factor. If the value has changed by more than 5 percent, recalibrate the meter over the full range of orifice settings, as previously detailed.
Note:
Alternative procedures, e.g., rechecking the orifice meter coefficient, may be used, subject to the approval of the Administrator.
10.3.3Acceptable variation in calibration. If the DGM coefficient values obtained before and after a test series differ by more than 5 percent, either the test series shall be voided or calculations for the test series shall be performed using whichever meter coefficient value (i.e., before or after) gives the lower value of total sample volume.
10.4Probe heater calibration. Use a heat source to generate air heated to selected temperatures that approximate those expected to occur in the sources to be sampled. Pass this air through the probe at a typical sample flow rate while measuring the probe inlet and outlet temperatures at various probe heater settings. For each air temperature generated, construct a graph of probe heating system setting versus probe outlet temperature. The procedure outlined in APTD-0576 can also be used. Probes constructed according to APTD-0581 need not be calibrated if the calibration curves in APTD-0576 are used. Also, probes with outlet temperature monitoring capabilities do not require calibration.
Note:
The probe heating system shall be calibrated before its initial use in the field.
10.5Temperature sensors. Use the procedure in section 10.3 of Method 2, 40 CFR part 60, appendix A to calibrate in-stack temperature sensors. Dial thermometers, such as are used for the DGM and condenser outlet, shall be calibrated against mercury-in-glass thermometers.
10.6Barometer. Calibrate against a mercury barometer.
11.0Analytical Procedure
11.1Record the data required on a sheet such as the one shown in Figure 315-1 of this method.
11.2Handle each sample container as follows:
11.2.1Container No. 1.
11.2.1.1PM analysis. Leave the contents in the shipping container or transfer the filter and any loose PM from the sample container to a tared glass weighing dish. Desiccate for 24 hours in a desiccator containing anhydrous calcium sulfate. Weigh to a constant weight and report the results to the nearest 0.1 mg. For purposes of this section, the term “constant weight” means a difference of no more than 0.5 mg or 1 percent of total weight less tare weight, whichever is greater, between two consecutive weighings, with no less than 6 hours of desiccation time between weighings (overnight desiccation is a common practice). If a third weighing is required and it agrees within ±0.5 mg, then the results of the second weighing should be used. For quality assurance purposes, record and report each individual weighing; if more than three weighings are required, note this in the results for the subsequent MCEM results.
11.2.1.2MCEM analysis. Transfer the filter and contents quantitatively into a beaker. Add 100 ml of methylene chloride and cover with aluminum foil. Sonicate for 3 minutes then allow to stand for 20 minutes. Set up the filtration apparatus. Decant the solution into a clean Buchner fritted funnel. Immediately pressure filter the solution through the tube into another clean, dry beaker. Continue decanting and pressure filtration until all the solvent is transferred. Rinse the beaker and filter with 10 to 20 ml methylene chloride, decant into the Buchner fritted funnel and pressure filter. Place the beaker on a low-temperature hot plate (maximum 40 °C) and slowly evaporate almost to dryness. Transfer the remaining last few milliliters of solution quantitatively from the beaker (using at least three aliquots of methylene chloride rinse) to a tared clean dry aluminum dish and evaporate to complete dryness. Remove from heat once solvent is evaporated. Reweigh the dish after a 30-minute equilibrium in the balance room and determine the weight to the nearest 0.1 mg. Conduct a methylene chloride blank run in an identical fashion.
11.2.2Container No. 2.
11.2.2.1PM analysis. Note the level of liquid in the container, and confirm on the analysis sheet whether leakage occurred during transport. If a noticeable amount of leakage has occurred, either void the sample or use methods, subject to the approval of the Administrator, to correct the final results. Measure the liquid in this container either volumetrically to ±1 ml or gravimetrically to 1 ±0.5 g. Transfer the contents to a tared 250 ml beaker and evaporate to dryness at ambient temperature and pressure. Desiccate for 24 hours, and weigh to a constant weight. Report the results to the nearest 0.1 mg.
11.2.2.2MCEM analysis. Add 25 ml methylene chloride to the beaker and cover with aluminum foil. Sonicate for 3 minutes then allow to stand for 20 minutes; combine with contents of Container No. 2M and pressure filter and evaporate as described for Container 1 in section 11.2.1.2 of this method.
Notes for MCEM Analysis
1. Light finger pressure only is necessary on 24/40 adaptor. A Chemplast adapter #15055-240 has been found satisfactory.
2. Avoid aluminum dishes made with fluted sides, as these may promote solvent “creep,” resulting in possible sample loss.
3. If multiple samples are being run, rinse the Buchner fritted funnel twice between samples with 5 ml solvent using pressure filtration. After the second rinse, continue the flow of air until the glass frit is completely dry. Clean the Buchner fritted funnels thoroughly after filtering five or six samples.
11.2.3Container No. 3. Weigh the spent silica gel (or silica gel plus impinger) to the nearest 0.5 g using a balance. This step may be conducted in the field.
11.2.4Container 3W (impinger water).
11.2.4.1MCEM analysis. Transfer the solution into a 1,000 ml separatory funnel quantitatively with methylene chloride washes. Add enough solvent to total approximately 50 ml, if necessary. Shake the funnel for 1 minute, allow the phases to separate, and drain the solvent layer into a 250 ml beaker. Repeat the extraction twice. Evaporate with low heat (less than 40 °C) until near dryness. Transfer the remaining few milliliters of solvent quantitatively with small solvent washes into a clean, dry, tared aluminum dish and evaporate to dryness. Remove from heat once solvent is evaporated. Reweigh the dish after a 30-minute equilibration in the balance room and determine the weight to the nearest 0.1 mg.
11.2.5Container 3S (solvent).
11.2.5.1MCEM analysis. Transfer the mixed solvent to 250 ml beaker(s). Evaporate and weigh following the procedures detailed for container 3W in section 11.2.4 of this method.
11.2.6Blank containers. Measure the distilled water, acetone, or methylene chloride in each container either volumetrically or gravimetrically. Transfer the “solvent” to a tared 250 ml beaker, and evaporate to dryness at ambient temperature and pressure. (Conduct a solvent blank on the distilled deionized water blank in an identical fashion to that described in section 11.2.4.1 of this method.) Desiccate for 24 hours, and weigh to a constant weight. Report the results to the nearest 0.l mg.
Note:
The contents of Containers No. 2, 3W, and 3M as well as the blank containers may be evaporated at temperatures higher than ambient. If evaporation is done at an elevated temperature, the temperature must be below the boiling point of the solvent; also, to prevent “bumping,” the evaporation process must be closely supervised, and the contents of the beaker must be swirled occasionally to maintain an even temperature. Use extreme care, as acetone and methylene chloride are highly flammable and have a low flash point.
12.0Data Analysis and Calculations
12.1Carry out calculations, retaining at least one extra decimal figure beyond that of the acquired data. Round off figures after the final calculation. Other forms of the equations may be used as long as they give equivalent results.
12.2Nomenclature.
An = Cross-sectional area of nozzle, m3 (ft3).
Bws = Water vapor in the gas stream, proportion by volume.
Ca = Acetone blank residue concentration, mg/g.
Cs = Concentration of particulate matter in stack gas, dry basis, corrected to standard conditions, g/dscm (g/dscf).
I = Percent of isokinetic sampling.
La = Maximum acceptable leakage rate for either a pretest leak check or for a leak check following a component change; equal to 0.00057 m3/min (0.02 cfm) or 4 percent of the average sampling rate, whichever is less.
Li = Individual leakage rate observed during the leak check conducted prior to the “ith” component change (I = l, 2, 3...n), m3/min (cfm).
Lp = Leakage rate observed during the post-test leak check, m3/min (cfm).
ma = Mass of residue of acetone after evaporation, mg.
mn = Total amount of particulate matter collected, mg.
Mw = Molecular weight of water, 18.0 g/g-mole (18.0 lb/lb-mole).
Pbar = Barometric pressure at the sampling site, mm Hg (in Hg).
Ps = Absolute stack gas pressure, mm Hg (in. Hg).
Pstd = Standard absolute pressure, 760 mm Hg (29.92 in. Hg).
R = Ideal gas constant, 0.06236 [(mm Hg)(m3)]/[(°K) (g-mole)] '61' 21.85 [(in. Hg)(ft3)]/[(°R)(lb-mole)'61' ].
Tm = Absolute average dry gas meter (DGM) temperature (see Figure 5-2 of Method 5, 40 CFR part 60, appendix A), °K (°R).
Ts = Absolute average stack gas temperature (see Figure 5-2 of Method 5, 40 CFR part 60, appendix A), °K(°R).
Tstd = Standard absolute temperature, 293 °K (528 °R).
Va = Volume of acetone blank, ml.
Vaw = Volume of acetone used in wash, ml.
Vt = Volume of methylene chloride blank, ml.
Vtw = Volume of methylene chloride used in wash, ml.
Vlc = Total volume liquid collected in impingers and silica gel (see Figure 5-3 of Method 5, 40 CFR part 60, appendix A), ml.
Vm = Volume of gas sample as measured by dry gas meter, dcm (dcf).
Vm(std) = Volume of gas sample measured by the dry gas meter, corrected to standard conditions, dscm (dscf).
Vw(std) = Volume of water vapor in the gas sample, corrected to standard conditions, scm (scf).
Vs = Stack gas velocity, calculated by Equation 2-9 in Method 2, 40 CFR part 60, appendix A, using data obtained from Method 5, 40 CFR part 60, appendix A, m/sec (ft/sec).
Wa = Weight of residue in acetone wash, mg.
Y = Dry gas meter calibration factor.
ΔH = Average pressure differential across the orifice meter (see Figure 5-2 of Method 5, 40 CFR part 60, appendix A), mm H2O (in H2O).
ρa = Density of acetone, 785.1 mg/ml (or see label on bottle).
ρw = Density of water, 0.9982 g/ml (0.00220l lb/ml).
ρt = Density of methylene chloride, 1316.8 mg/ml (or see label on bottle).
Θ = Total sampling time, min.
Θ1 = Sampling time interval, from the beginning of a run until the first component change, min.
Θ1 = Sampling time interval, between two successive component changes, beginning with the interval between the first and second changes, min.
Θp = Sampling time interval, from the final (nth) component change until the end of the sampling run, min.
13.6 = Specific gravity of mercury.
60 = Sec/min.
100 = Conversion to percent.
12.3 Average dry gas meter temperature and average orifice pressure drop. See data sheet (Figure 5-2 of Method 5, 40 CFR part 60, appendix A).
12.4 Dry gas volume. Correct the sample volume measured by the dry gas meter to standard conditions (20 °C, 760 mm Hg or 68 °F, 29.92 in Hg) by using Equation 315-1.
Where
Kl = 0.3858 °K/mm Hg for metric units,
= 17.64 °R/in Hg for English units.
Note:
Equation 315-1 can be used as written unless the leakage rate observed during any of the mandatory leak checks (i.e., the post-test leak check or leak checks conducted prior to component changes) exceeds La. If Lp or Li exceeds La, Equation 315-1 must be modified as follows:
(a) Case I. No component changes made during sampling run. In this case, replace Vm in Equation 315-1 with the expression:
[Vm—(Lp—La) Θ]
(b) Case II. One or more component changes made during the sampling run. In this case, replace Vm in Equation 315-1 by the expression:
and substitute only for those leakage rates (Li or Lp) which exceed La.
12.5Volume of water vapor condensed.
Where
K2 = 0.001333 m3/ml for metric units;
= 0.04706 ft3/ml for English units.
12.6Moisture content.
Note:
In saturated or water droplet-laden gas streams, two calculations of the moisture content of the stack gas shall be made, one from the impinger analysis (Equation 315-3), and a second from the assumption of saturated conditions. The lower of the two values of Bws shall be considered correct. The procedure for determining the moisture content based upon assumption of saturated conditions is given in section 4.0 of Method 4, 40 CFR part 60, appendix A. For the purposes of this method, the average stack gas temperature from Figure 5-2 of Method 5, 40 CFR part 60, appendix A may be used to make this determination, provided that the accuracy of the in-stack temperature sensor is ±1 °C (2 °F).
12.7Acetone blank concentration.
12.8Acetone wash blank.
Wa = Ca Vaw ρa Eq. 315-5
12.9Total particulate weight. Determine the total PM catch from the sum of the weights obtained from Containers l and 2 less the acetone blank associated with these two containers (see Figure 315-1).
Note:
Refer to section 8.5.8 of this method to assist in calculation of results involving two or more filter assemblies or two or more sampling trains.
12.10Particulate concentration.
cs = K3 mn/Vm(std)Eq. 315-6
where
K = 0.001 g/mg for metric units;
= 0.0154 gr/mg for English units.
12.11Conversion factors.
From To Multiply by
ft 3 m 3 0.02832
gr mg 64.80004
gr/ft3 mg/m3 2288.4
mg g 0.001
gr lb 1.429×10−4
12.12Isokinetic variation.
12.12.1Calculation from raw data.
where
K4 = 0.003454 [(mm Hg)(m3)]/[(m1)(°K)] for metric units;
= 0.002669 [(in Hg)(ft3)]/[(m1)(°R)] for English units.
12.12.2Calculation from intermediate values.
where
K5 = 4.320 for metric units;
= 0.09450 for English units.
12.12.3Acceptable results. If 90 percent ≤ I ≤ 110 percent, the results are acceptable. If the PM or MCEM results are low in comparison to the standard, and “I” is over 110 percent or less than 90 percent, the Administrator may opt to accept the results. Reference 4 in the Bibliography may be used to make acceptability judgments. If “I” is judged to be unacceptable, reject the results, and repeat the test.
12.13Stack gas velocity and volumetric flow rate. Calculate the average stack gas velocity and volumetric flow rate, if needed, using data obtained in this method and the equations in sections 5.2 and 5.3 of Method 2, 40 CFR part 60, appendix A.
12.14MCEM results. Determine the MCEM concentration from the results from Containers 1, 2, 2M, 3W, and 3S less the acetone, methylene chloride, and filter blanks value as determined in the following equation:
m mcem = Sm totalw aw tf b
13.0Method Performance [Reserved]
14.0Pollution Prevention [Reserved]
15.0Waste Management [Reserved]
16.0Alternative Procedures
16.1Dry gas meter as a calibration standard. A DGM may be used as a calibration standard for volume measurements in place of the wet test meter specified in section 16.1 of this method, provided that it is calibrated initially and recalibrated periodically as follows:
16.1.1 Standard dry gas meter calibration.
16.1.1.1. The DGM to be calibrated and used as a secondary reference meter should be of high quality and have an appropriately sized capacity, e.g., 3 liters/rev (0.1 ft 3/rev). A spirometer (400 liters or more capacity), or equivalent, may be used for this calibration, although a wet test meter is usually more practical. The wet test meter should have a capacity of 30 liters/rev (1 ft 3/rev) and be capable of measuring volume to within 1.0 percent; wet test meters should be checked against a spirometer or a liquid displacement meter to ensure the accuracy of the wet test meter. Spirometers or wet test meters of other sizes may be used, provided that the specified accuracies of the procedure are maintained.
16.1.1.2Set up the components as shown in Figure 5-7 of Method 5, 40 CFR part 60, appendix A. A spirometer, or equivalent, may be used in place of the wet test meter in the system. Run the pump for at least 5 minutes at a flow rate of about 10 liters/min (0.35 cfm) to condition the interior surface of the wet test meter. The pressure drop indicated by the manometer at the inlet side of the DGM should be minimized (no greater than 100 mm H2O [4 in. H2O] at a flow rate of 30 liters/min [1 cfm]). This can be accomplished by using large-diameter tubing connections and straight pipe fittings.
16.1.1.3Collect the data as shown in the example data sheet (see Figure 5-8 of Method 5, 40 CFR part 60, appendix A). Make triplicate runs at each of the flow rates and at no less than five different flow rates. The range of flow rates should be between 10 and 34 liters/min (0.35 and 1.2 cfm) or over the expected operating range.
16.1.1.4Calculate flow rate, Q, for each run using the wet test meter volume, Vw, and the run time, q. Calculate the DGM coefficient, Yds, for each run. These calculations are as follows:
Where
K1 = 0.3858 for international system of units (SI); 17.64 for English units;
Pbar = Barometric pressure, mm Hg (in Hg);
Vw = Wet test meter volume, liter (ft3);
tw = Average wet test meter temperature, °C (°F);
tstd = 273 °C for SI units; 460 °F for English units;
Θ = Run time, min;
tds = Average dry gas meter temperature, °C (°F);
Vds = Dry gas meter volume, liter (ft3);
Δp = Dry gas meter inlet differential pressure, mm H2O (in H2O).
16.1.1.5Compare the three Yds values at each of the flow rates and determine the maximum and minimum values. The difference between the maximum and minimum values at each flow rate should be no greater than 0.030. Extra sets of triplicate runs may be made in order to complete this requirement. In addition, the meter coefficients should be between 0.95 and 1.05. If these specifications cannot be met in three sets of successive triplicate runs, the meter is not suitable as a calibration standard and should not be used as such. If these specifications are met, average the three Yds values at each flow rate resulting in five average meter coefficients, Yds.
16.1.1.6Prepare a curve of meter coefficient, Yds, versus flow rate, Q, for the DGM. This curve shall be used as a reference when the meter is used to calibrate other DGMs and to determine whether recalibration is required.
16.1.2Standard dry gas meter recalibration.
16.1.2.1Recalibrate the standard DGM against a wet test meter or spirometer annually or after every 200 hours of operation, whichever comes first. This requirement is valid provided the standard DGM is kept in a laboratory and, if transported, cared for as any other laboratory instrument. Abuse to the standard meter may cause a change in the calibration and will require more frequent recalibrations.
16.1.2.2As an alternative to full recalibration, a two-point calibration check may be made. Follow the same procedure and equipment arrangement as for a full recalibration, but run the meter at only two flow rates (suggested rates are 14 and 28 liters/min [0.5 and 1.0 cfm]). Calculate the meter coefficients for these two points, and compare the values with the meter calibration curve. If the two coefficients are within 1.5 percent of the calibration curve values at the same flow rates, the meter need not be recalibrated until the next date for a recalibration check.
6.2Critical orifices as calibration standards. Critical orifices may be used as calibration standards in place of the wet test meter specified in section 10.3 of this method, provided that they are selected, calibrated, and used as follows:
16.2.1Selection of critical orifices.
16.2.1.1The procedure that follows describes the use of hypodermic needles or stainless steel needle tubing that has been found suitable for use as critical orifices. Other materials and critical orifice designs may be used provided the orifices act as true critical orifices; i.e., a critical vacuum can be obtained, as described in section 7.2.2.2.3 of Method 5, 40 CFR part 60, appendix A. Select five critical orifices that are appropriately sized to cover the range of flow rates between 10 and 34 liters/min or the expected operating range. Two of the critical orifices should bracket the expected operating range. A minimum of three critical orifices will be needed to calibrate a Method 5 DGM; the other two critical orifices can serve as spares and provide better selection for bracketing the range of operating flow rates. The needle sizes and tubing lengths shown in Table 315-1 give the approximate flow rates indicated in the table.
16.2.1.2These needles can be adapted to a Method 5 type sampling train as follows: Insert a serum bottle stopper, 13×20 mm sleeve type, into a 0.5 in Swagelok quick connect. Insert the needle into the stopper as shown in Figure 5-9 of Method 5, 40 CFR part 60, appendix A.
16.2.2Critical orifice calibration. The procedure described in this section uses the Method 5 meter box configuration with a DGM as described in section 6.1.1.9 of this method to calibrate the critical orifices. Other schemes may be used, subject to the approval of the Administrator.
16.2.2.1Calibration of meter box. The critical orifices must be calibrated in the same configuration as they will be used; i.e., there should be no connections to the inlet of the orifice.
16.2.2.1.1Before calibrating the meter box, leak-check the system as follows: Fully open the coarse adjust valve and completely close the bypass valve. Plug the inlet. Then turn on the pump and determine whether there is any leakage. The leakage rate shall be zero; i.e., no detectable movement of the DGM dial shall be seen for 1 minute.
16.2.2.1.2Check also for leakages in that portion of the sampling train between the pump and the orifice meter. See section 5.6 of Method 5, 40 CFR part 60, appendix A for the procedure; make any corrections, if necessary. If leakage is detected, check for cracked gaskets, loose fittings, worn 0-rings, etc. and make the necessary repairs.
16.2.2.1.3After determining that the meter box is leakless, calibrate the meter box according to the procedure given in section 5.3 of Method 5, 40 CFR part 60, appendix A. Make sure that the wet test meter meets the requirements stated in section 7.1.1.1 of Method 5, 40 CFR part 60, appendix A. Check the water level in the wet test meter. Record the DGM calibration factor, Y.
16.2.2.2Calibration of critical orifices. Set up the apparatus as shown in Figure 5-10 of Method 5, 40 CFR part 60, appendix A.
16.2.2.2.1Allow a warm-up time of 15 minutes. This step is important to equilibrate the temperature conditions through the DGM.
16.2.2.2.2Leak-check the system as in section 7.2.2.1.1 of Method 5, 40 CFR part 60, appendix A. The leakage rate shall be zero.
16.2.2.2.3Before calibrating the critical orifice, determine its suitability and the appropriate operating vacuum as follows: turn on the pump, fully open the coarse adjust valve, and adjust the bypass valve to give a vacuum reading corresponding to about half of atmospheric pressure. Observe the meter box orifice manometer reading, DH. Slowly increase the vacuum reading until a stable reading is obtained on the meter box orifice manometer. Record the critical vacuum for each orifice. Orifices that do not reach a critical value shall not be used.
16.2.2.2.4Obtain the barometric pressure using a barometer as described in section 6.1.2 of this method. Record the barometric pressure, Pbar, in mm Hg (in. Hg).
16.2.2.2.5Conduct duplicate runs at a vacuum of 25 to 50 mm Hg (1 to 2 in. Hg) above the critical vacuum. The runs shall be at least 5 minutes each. The DGM volume readings shall be in increments of complete revolutions of the DGM. As a guideline, the times should not differ by more than 3.0 seconds (this includes allowance for changes in the DGM temperatures) to achieve ±0.5 percent in K′. Record the information listed in Figure 5-11 of Method 5, 40 CFR part 60, appendix A.
16.2.2.2.6 Calculate K′ using Equation 315-11.
where
K′ = Critical orifice coefficient, [m3)(°K)1/2]/[(mm Hg)(min)] [(ft3)(°R)1/2)]/[(in. Hg)(min)]
Tamb = Absolute ambient temperature, °K (°R).
16.2.2.2.7Average the K′ values. The individual K′ values should not differ by more than ±0.5 percent from the average.
16.2.3Using the critical orifices as calibration standards.
16.2.3.1Record the barometric pressure.
16.2.3.2Calibrate the metering system according to the procedure outlined in sections 7.2.2.2.1 to 7.2.2.2.5 of Method 5, 40 CFR part 60, appendix A. Record the information listed in Figure 5-12 of Method 5, 40 CFR part 60, appendix A.
16.2.3.3Calculate the standard volumes of air passed through the DGM and the critical orifices, and calculate the DGM calibration factor, Y, using the equations below:
Vm(std) = K1 Vm [Pbar (ΔH/13.6)]/Tm Eq. 315-12
Vcr(std) = K′ (Pbar Θ)/Tamb 1/2 Eq. 315-13
Y = Vcr(std)/Vm(std) Eq. 315-14
where
Vcr(std) = Volume of gas sample passed through the critical orifice, corrected to standard conditions, dscm (dscf).
K′ = 0.3858 °K/mm Hg for metric units
= 17.64 °R/in Hg for English units.
16.2.3.4Average the DGM calibration values for each of the flow rates. The calibration factor, Y, at each of the flow rates should not differ by more than ±2 percent from the average.
16.2.3.5To determine the need for recalibrating the critical orifices, compare the DGM Y factors obtained from two adjacent orifices each time a DGM is calibrated; for example, when checking orifice 13/2.5, use orifices 12/10.2 and 13/5.1. If any critical orifice yields a DGM Y factor differing by more than 2 percent from the others, recalibrate the critical orifice according to section 7.2.2.2 of Method 5, 40 CFR part 60, appendix A.
17.0References
1. Addendum to Specifications for Incinerator Testing at Federal Facilities. PHS, NCAPC. December 6, 1967.
2. Martin, Robert M. Construction Details of Isokinetic Source-Sampling Equipment. Environmental Protection Agency. Research Triangle Park, NC. APTD-0581. April 1971.
3. Rom, Jerome J. Maintenance, Calibration, and Operation of Isokinetic Source Sampling Equipment. Environmental Protection Agency. Research Triangle Park, NC. APTD-0576. March 1972.
4. Smith, W.S., R.T. Shigehara, and W.F. Todd. A Method of Interpreting Stack Sampling Data. Paper Presented at the 63rd Annual Meeting of the Air Pollution Control Association, St. Louis, MO. June 14-19, 1970.
5. Smith, W.S., et al. Stack Gas Sampling Improved and Simplified With New Equipment. APCA Paper No. 67-119. 1967.
6. Specifications for Incinerator Testing at Federal Facilities. PHS, NCAPC. 1967.
7. Shigehara, R.T. Adjustment in the EPA Nomograph for Different Pitot Tube Coefficients and Dry Molecular Weights. Stack Sampling News 2:4-11. October 1974.
8. Vollaro, R.F. A Survey of Commercially Available Instrumentation for the Measurement of Low-Range Gas Velocities. U.S. Environmental Protection Agency, Emission Measurement Branch. Research Triangle Park, NC. November 1976 (unpublished paper).
9. Annual Book of ASTM Standards. Part 26. Gaseous Fuels; Coal and Coke; Atmospheric Analysis. American Society for Testing and Materials. Philadelphia, PA. 1974. pp. 617-622.
10. Felix, L.G., G.I. Clinard, G.E. Lacy, and J.D. McCain. Inertial Cascade Impactor Substrate Media for Flue Gas Sampling. U.S. Environmental Protection Agency. Research Triangle Park, NC 27711. Publication No. EPA-600/7-77-060. June 1977. 83 p.
11. Westlin, P.R., and R.T. Shigehara. Procedure for Calibrating and Using Dry Gas Volume Meters as Calibration Standards. Source Evaluation Society Newsletter. 3(1):17-30. February 1978.
12. Lodge, J.P., Jr., J.B. Pate, B.E. Ammons, and G.A. Swanson. The Use of Hypodermic Needles as Critical Orifices in Air Sampling. J. Air Pollution Control Association. 16:197-200. 1966.
18.0Tables, Diagrams, Flowcharts, and Validation Data
Table 315-1. Flow Rates for Various Needle Sizes and Tube Lengths.
Gauge/length(cm) Flow rate(liters/min) Gauge/length(cm) Flow rate(liters/min)
12/7.6 32.56 14/2.5 19.54
12/10.2 30.02 14/5.1 17.27
13/2.5 25.77 14/7.6 16.14
13/5.1 23.50 15/3.2 14.16
13/7.6 22.37 15/7.6 11.61
13/10.2 20.67 115/10.2 10.48
Figure 315-1. Particulate and MCEM Analyses
Particulate Analysis
Plant
Date
Run No.
Filter No.
Amount liquid lost during transport
Acetone blank volume (ml)
Acetone blank concentration (Eq. 315-4) (mg/mg)
Acetone wash blank (Eq. 315-5) (mg)
Final weight(mg) Tare weight(mg) Weight gain(mg)
Container No. 1
Container No. 2
Total
Less Acetone blank
Weight of particulate matter
Final volume (mg) Initial volume (mg) Liquid collected (mg)
Moisture Analysis
Impingers Note 1 Note 1
Silica gel
Total
Note 1: Convert volume of water to weight by multiplying by the density of water (1 g/ml).
Container No. Final weight (mg) Tare of aluminum dish (mg) Weight gain Acetone wash volume (ml) Methylene chloride wash volume (ml)
MCEM Analysis
1
2 2M
3W
3S
Total m total 0 V aw V tw
Less acetone wash blank (mg) (not to exceed 1 mg/l of acetone used) w a = c a p aV aw
Less methylene chloride wash blank (mg) (not to exceed 1.5 mg/l of methylene chloride used) w t = c t p tV tw
Less filter blank (mg) (not to exceed . . . (mg/filter) F b
MCEM weight (mg) m MCEOM = ∑m totalw aw tf b
Method 316—Sampling and Analysis for Formaldehyde Emissions From Stationary Sources in the Mineral Wool and Wool Fiberglass Industries
1.0Introduction
This method is applicable to the determination of formaldehyde, CAS Registry number 50-00-0, from stationary sources in the mineral wool and wool fiber glass industries. High purity water is used to collect the formaldehyde. The formaldehyde concentrations in the stack samples are determined using the modified pararosaniline method. Formaldehyde can be detected as low as 8.8 × 1010 lbs/cu ft (11.3 ppbv) or as high as 1.8 × 103 lbs/cu ft (23,000,000 ppbv), at standard conditions over a 1 hour sampling period, sampling approximately 30 cu ft.
2.0Summary of Method
Gaseous and particulate pollutants are withdrawn isokinetically from an emission source and are collected in high purity water. Formaldehyde present in the emissions is highly soluble in high purity water. The high purity water containing formaldehyde is then analyzed using the modified pararosaniline method. Formaldehyde in the sample reacts with acidic pararosaniline, and the sodium sulfite, forming a purple chromophore. The intensity of the purple color, measured spectrophotometrically, provides an accurate and precise measure of the formaldehyde concentration in the sample.
3.0Definitions
See the definitions in the General Provisions of this Subpart.
4.0Interferences
Sulfite and cyanide in solution interfere with the pararosaniline method. A procedure to overcome the interference by each compound has been described by Miksch, et al.
5.0Safety [Reserved]
6.0Apparatus and Materials
6.1A schematic of the sampling train is shown in Figure 1. This sampling train configuration is adapted from EPA Method 5, 40 CFR part 60, appendix A, procedures.
The sampling train consists of the following components: probe nozzle, probe liner, pitot tube, differential pressure gauge, impingers, metering system, barometer, and gas density determination equipment.
6.1.1Probe Nozzle:Quartz, glass, or stainless steel with sharp, tapered (30 ° angle) leading edge. The taper shall be on the outside to preserve a constant inner diameter. The nozzle shall be buttonhook or elbow design. A range of nozzle sizes suitable for isokinetic sampling should be available in increments of 0.15 cm (1/16 in), e.g., 0.32 to 1.27 cm (1/8 to 1/2 in), or larger if higher volume sampling trains are used. Each nozzle shall be calibrated according to the procedure outlined in Section 10.1.
6.1.2Probe Liner: Borosilicate glass or quartz shall be used for the probe liner. The probe shall be maintained at a temperature of 120 °C ±14 °C (248 °F ±25 °F).
6.1.3Pitot Tube: The pitot tube shall be Type S, as described in Section 2.1 of EPA Method 2, 40 CFR part 60, appendix A, or any other appropriate device. The pitot tube shall be attached to the probe to allow constant monitoring of the stack gas velocity. The impact (high pressure) opening plane of the pitot tube shall be even with or above the nozzle entry plane (see Figure 2-6b, EPA Method 2, 40 CFR part 60, appendix A) during sampling. The Type S pitot tube assembly shall have a known coefficient, determined as outlined in Section 4 of EPA Method 2, 40 CFR part 60, appendix A.
6.1.4Differential Pressure Gauge: The differential pressure gauge shall be an inclined manometer or equivalent device as described in Section 2.2 of EPA Method 2, 40 CFR part 60, appendix A. One manometer shall be used for velocity-head reading and the other for orifice differential pressure readings.
6.1.5Impingers: The sampling train requires a minimum of four impingers, connected as shown in Figure 1, with ground glass (or equivalent) vacuum-tight fittings. For the first, third, and fourth impingers, use the Greenburg-Smith design, modified by replacing the tip with a 1.3 cm inside diameters (1/2 in) glass tube extending to 1.3 cm (1/2 in) from the bottom of the flask. For the second impinger, use a Greenburg-Smith impinger with the standard tip. Place a thermometer capable of measuring temperature to within 1 °C (2 °F) at the outlet of the fourth impinger for monitoring purposes.
6.1.6Metering System: The necessary components are a vacuum gauge, leak-free pump, thermometers capable of measuring temperatures within 3 °C (5.4 °F), dry-gas meter capable of measuring volume to within 1 percent, and related equipment as shown in Figure 1. At a minimum, the pump should be capable of 4 cfm free flow, and the dry gas meter should have a recording capacity of 0-999.9 cu ft with a resolution of 0.005 cu ft. Other metering systems may be used which are capable of maintaining sample volumes to within 2 percent. The metering system may be used in conjunction with a pitot tube to enable checks of isokinetic sampling rates.
6.1.7Barometer: The barometer may be mercury, aneroid, or other barometer capable of measuring atmospheric pressure to within 2.5 mm Hg (0.1 in Hg). In many cases, the barometric reading may be obtained from a nearby National Weather Service Station, in which case the station value (which is the absolute barometric pressure) is requested and an adjustment for elevation differences between the weather station and sampling point is applied at a rate of minus 2.5 mm Hg (0.1 in Hg) per 30 m (100 ft) elevation increase (rate is plus 2.5 mm Hg per 30 m (100 ft) of elevation decrease).
6.1.8Gas Density Determination Equipment: Temperature sensor and pressure gauge (as described in Sections 2.3 and 2.3 of EPA Method 2, 40 CFR part 60, appendix A), and gas analyzer, if necessary (as described in EPA Method 3, 40 CFR part 60, appendix A). The temperature sensor ideally should be permanently attached to the pitot tube or sampling probe in a fixed configuration such that the top of the sensor extends beyond the leading edge of the probe sheath and does not touch any metal. Alternatively, the sensor may be attached just prior to use in the field. Note, however, that if the temperature sensor is attached in the field, the sensor must be placed in an interference-free arrangement with respect to the Type S pitot openings (see Figure 2-7, EPA Method 2, 40 CFR part 60, appendix A). As a second alternative, if a difference of no more than 1 percent in the average velocity measurement is to be introduced, the temperature gauge need not be attached to the probe or pitot tube.
6.2Sample Recovery
6.2.1Probe Liner: Probe nozzle and brushes; bristle brushes with stainless steel wire handles are required. The probe brush shall have extensions of stainless steel, Teflon TM, or inert material at least as long as the probe. The brushes shall be properly sized and shaped to brush out the probe liner, the probe nozzle, and the impingers.
6.2.2Wash Bottles: One wash bottle is required. Polyethylene, Teflon TM, or glass wash bottles may be used for sample recovery.
6.2.3Graduated Cylinder and/or Balance: A graduated cylinder or balance is required to measure condensed water to the nearest 1 ml or 1 g. Graduated cylinders shall have division not >2 ml. Laboratory balances capable of weighing to ±0.5 g are required.
6.2.4Polyethylene Storage Containers: 500 ml wide-mouth polyethylene bottles are required to store impinger water samples.
6.2.5Rubber Policeman and Funnel: A rubber policeman and funnel are required to aid the transfer of material into and out of containers in the field.
6.3Sample Analysis
6.3.1Spectrophotometer—B&L 70, 710, 2000, etc., or equivalent; 1 cm pathlength cuvette holder.
6.3.2Disposable polystyrene cuvettes, pathlengh 1 cm, volume of about 4.5 ml.
6.3.3Pipettors—Fixed-volume Oxford pipet (250 µl; 500 µl; 1000 µl); adjustable volume Oxford or equivalent pipettor 1-5 ml model, set to 2.50 ml.
6.3.4Pipet tips for pipettors above.
6.3.5Parafilm, 2 ° wide; cut into about 1” squares.
7.0Reagents
7.1High purity water: All references to water in this method refer to high purity water (ASTM Type I water or equivalent). The water purity will dictate the lower limits of formaldehyde quantification.
7.2Silica Gel: Silica gel shall be indicting type, 6-16 mesh. If the silica gel has been used previously, dry at 175 °C (350 °F) for 2 hours before using. New silica gel may be used as received. Alternatively, other types of desiccants (equivalent or better) may be used.
7.3Crushed Ice: Quantities ranging from 10-50 lbs may be necessary during a sampling run, depending upon ambient temperature. Samples which have been taken must be stored and shipped cold; sufficient ice for this purpose must be allowed.
7.4Quaternary ammonium compound stock solution: Prepare a stock solution of dodecyltrimethylammonium chloride (98 percent minimum assay, reagent grade) by dissolving 1.0 gram in 1000 ml water. This solution contains nominally 1000 µg/ml quaternary ammonium compound, and is used as a biocide for some sources which are prone to microbial contamination.
7.5Pararosaniline: Weigh 0.16 grams pararosaniline (free base; assay of 95 percent or greater, C.I. 42500; Sigma P7632 has been found to be acceptable) into a 100 ml flask. Exercise care, since pararosaniline is a dye and will stain. Using a wash bottle with high-purity water, rinse the walls of the flask. Add no more than 25 ml water. Then, carefully add 20 ml of concentrated hydrochloric acid to the flask. The flask will become warm after the addition of acid. Add a magnetic stir bar to the flask, cap, and place on a magnetic stirrer for approximately 4 hours. Then, add additional water so the total volume is 100 ml. This solution is stable for several months when stored tightly capped at room temperature.
7.6Sodium sulfite: Weigh 0.10 grams anhydrous sodium sulfite into a 100 ml flask. Dilute to the mark with high purity water. Invert 15-20 times to mix and dissolve the sodium sulfite. This solution must be prepared fresh every day.
7.7Formaldehyde standard solution: Pipet exactly 2.70 ml of 37 percent formaldehyde solution into a 1000 ml volumetric flask which contains about 500 ml of high-purity water. Dilute to the mark with high-purity water. This solution contains nominally 1000 µg/ml of formaldehyde, and is used to prepare the working formaldehyde standards. The exact formaldehyde concentration may be determined if needed by suitable modification of the sodium sulfite method (Reference: J.F. Walker, Formaldehyde (Third Edition), 1964.). The 1000 µg/ml formaldehyde stock solution is stable for at least a year if kept tightly closed, with the neck of the flask sealed with Parafilm. Store at room temperature.
7.8Working formaldehyde standards: Pipet exactly 10.0 ml of the 1000 µg/ml formaldehyde stock solution into a 100 ml volumetric flask which is about half full of high-purity water. Dilute to the mark with high-purity water, and invert 15-20 times to mix thoroughly. This solution contains nominally 100 µg/ml formaldehyde. Prepare the working standards from this 100 µg/ml standard solution and using the Oxford pipets:
Working standard, µ/mL µL or 100 µg/mL solution Volumetric flask volume (dilute to mark with water)
0.250 250 100
0.500 500 100
1.00 1000 100
2.00 2000 100
3.00 1500 50
The 100 µg/ml stock solution is stable for 4 weeks if kept refrigerated between analyses. The working standards (0.25-3.00 µg/ml) should be prepared fresh every day, consistent with good laboratory practice for trace analysis. If the laboratory water is not of sufficient purity, it may be necessary to prepare the working standards every day. The laboratory must establish that the working standards are stable—DO NOT assume that your working standards are stable for more than a day unless you have verified this by actual testing for several series of working standards.
8.0Sample Collection
8.1Because of the complexity of this method, field personnel should be trained in and experienced with the test procedures in order to obtain reliable results.
8.2Laboratory Preparation
8.2.1All the components shall be maintained and calibrated according to the procedure described in APTD-0576, unless otherwise specified.
8.2.2Weigh several 200 to 300 g portions of silica gel in airtight containers to the nearest 0.5 g. Record on each container the total weight of the silica gel plus containers. As an alternative to preweighing the silica gel, it may instead be weighed directly in the impinger or sampling holder just prior to train assembly.
8.3Preliminary Field Determinations
8.3.1Select the sampling site and the minimum number of sampling points according to EPA Method 1, 40 CFR part 60, appendix A, or other relevant criteria. Determine the stack pressure, temperature, and range of velocity heads using EPA Method 2, 40 CFR part 60, appendix A. A leak-check of the pitot lines according to Section 3.1 of EPA Method 2, 40 CFR part 60, appendix A, must be performed. Determine the stack gas moisture content using EPA Approximation Method 4,40 CFR part 60, appendix A, or its alternatives to establish estimates of isokinetic sampling rate settings. Determine the stack gas dry molecular weight, as described in EPA Method 2, 40 CFR part 60, appendix A, Section 3.6. If integrated EPA Method 3, 40 CFR part 60, appendix A, sampling is used for molecular weight determination, the integrated bag sample shall be taken simultaneously with, and for the same total length of time as, the sample run.
8.3.2Select a nozzle size based on the range of velocity heads so that it is not necessary to change the nozzle size in order to maintain isokinetic sampling rates below 28 l/min (1.0 cfm). During the run do not change the nozzle. Ensure that the proper differential pressure gauge is chosen for the range of velocity heads encountered (see Section 2.2 of EPA Method 2, 40 CFR part 60, appendix A).
8.3.3Select a suitable probe liner and probe length so that all traverse points can be sampled. For large stacks, to reduce the length of the probe, consider sampling from opposite sides of the stack.
8.3.4A minimum of 30 cu ft of sample volume is suggested for emission sources with stack concentrations not greater than 23,000,000 ppbv. Additional sample volume shall be collected as necessitated by the capacity of the water reagent and analytical detection limit constraint. Reduced sample volume may be collected as long as the final concentration of formaldehyde in the stack sample is greater than 10 (ten) times the detection limit.
8.3.5Determine the total length of sampling time needed to obtain the identified minimum volume by comparing the anticipated average sampling rate with the volume requirement. Allocate the same time to all traverse points defined by EPA Method 1, 40 CFR part 60, appendix A. To avoid timekeeping errors, the length of time sampled at each traverse point should be an integer or an integer plus 0.5 min.
8.3.6In some circumstances (e.g., batch cycles) it may be necessary to sample for shorter times at the traverse points and to obtain smaller gas-volume samples. In these cases, careful documentation must be maintained in order to allow accurate calculations of concentrations.
8.4Preparation of Collection Train
8.4.1During preparation and assembly of the sampling train, keep all openings where contamination can occur covered with TeflonTM film or aluminum foil until just prior to assembly or until sampling is about to begin.
8.4.2Place 100 ml of water in each of the first two impingers, and leave the third impinger empty. If additional capacity is required for high expected concentrations of formaldehyde in the stack gas, 200 ml of water per impinger may be used or additional impingers may be used for sampling. Transfer approximately 200 to 300 g of pre-weighed silica gel from its container to the fourth impinger. Care should be taken to ensure that the silica gel is not entrained and carried out from the impinger during sampling. Place the silica gel container in a clean place for later use in the sample recovery. Alternatively, the weight of the silica gel plus impinger may be determined to the nearest 0.5 g and recorded.
8.4.3With a glass or quartz liner, install the selected nozzle using a Viton-A O-ring when stack temperatures are <260 °C (500 °F) and a woven glass-fiber gasket when temperatures are higher. See APTD-0576 for details. Other connection systems utilizing either 316 stainless steel or TeflonTM ferrules may be used. Mark the probe with heat-resistant tape or by some other method to denote the proper distance into the stack or duct for each sampling point.
8.4.4Assemble the train as shown in Figure 1. During assembly, a very light coating of silicone grease may be used on ground-glass joints of the impingers, but the silicone grease should be limited to the outer portion (see APTD-0576) of the ground-glass joints to minimize silicone grease contamination. If necessary, TeflonTM tape may be used to seal leaks. Connect all temperature sensors to an appropriate potentiometer/display unit. Check all temperature sensors at ambient temperatures.
8.4.5Place crushed ice all around the impingers.
8.4.6Turn on and set the probe heating system at the desired operating temperature. Allow time for the temperature to stabilize.
8.5Leak-Check Procedures
8.5.1Pre-test Leak-check: Recommended, but not required. If the tester elects to conduct the pre-test leak-check, the following procedure shall be used.
8.5.1.1After the sampling train has been assembled, turn on and set probe heating system at the desired operating temperature. Allow time for the temperature to stabilize. If a Viton-a O-ring or other leak-free connection is used in assembling the probe nozzle to the probe liner, leak-check the train at the sampling site by plugging the nozzle and pulling a 381 mm Hg (15 in Hg) vacuum.
Note:
A lower vacuum may be used, provided that the lower vacuum is not exceeded during the test.
If a woven glass fiber gasket is used, do not connect the probe to the train during the leak-check. Instead, leak-check the train by first attaching a carbon-filled leak-check impinger to the inlet and then plugging the inlet and pulling a 381 mm Hg (15 in Hg) vacuum. (A lower vacuum may be used if this lower vacuum is not exceeded during the test.) Next connect the probe to the train and leak-check at about 25 mm Hg (1 in Hg) vacuum. Alternatively, leak-check the probe with the rest of the sampling train in one step at 381 mm Hg (15 in Hg) vacuum. Leakage rates in excess of (a) 4 percent of the average sampling rate or (b) 0.00057 m3/min (0.02 cfm), whichever is less, are unacceptable.
8.5.1.2The following leak-check instructions for the sampling train described in APTD-0576 and APTD-0581 may be helpful. Start the pump with the fine-adjust valve fully open and coarse-valve completely closed. Partially open the coarse-adjust valve and slowly close the fine-adjust valve until the desired vacuum is reached. Do not reverse direction of the fine-adjust valve, as liquid will back up into the train. If the desired vacuum is exceeded, either perform the leak-check at this higher vacuum or end the leak-check, as described below, and start over.
8.5.1.3When the leak-check is completed, first slowly remove the plug from the inlet to the probe. When the vacuum drops to 127 mm (5 in) Hg or less, immediately close the coarse-adjust valve. Switch off the pumping system and reopen the fine-adjust valve. Do not reopen the fine-adjust valve until the coarse-adjust valve has been closed to prevent the liquid in the impingers from being forced backward in the sampling line and silica gel from being entrained backward into the third impinger.
8.5.2Leak-checks During Sampling Run:
8.5.2.1If, during the sampling run, a component change (e.g., impinger) becomes necessary, a leak-check shall be conducted immediately after the interruption of sampling and before the change is made. The leak-check shall be done according to the procedure described in Section 10.3.3, except that it shall be done at a vacuum greater than or equal to the maximum value recorded up to that point in the test. If the leakage rate is found to be no greater than 0.0057 m3/min (0.02 cfm) or 4 percent of the average sampling rate (whichever is less), the results are acceptable. If a higher leakage rate is obtained, the tester must void the sampling run.
Note:
Any correction of the sample volume by calculation reduces the integrity of the pollutant concentration data generated and must be avoided.
8.5.2.2Immediately after component changes, leak-checks are optional. If performed, the procedure described in section 8.5.1.1 shall be used.
8.5.3Post-test Leak-check:
8.5.3.1A leak-check is mandatory at the conclusion of each sampling run. The leak-check shall be done with the same procedures as the pre-test leak-check, except that the post-test leak-check shall be conducted at a vacuum greater than or equal to the maximum value reached during the sampling run. If the leakage rate is found to be no greater than 0.00057 m3/min (0.02 cfm) or 4 percent of the average sampling rate (whichever is less), the results are acceptable. If, however, a higher leakage rate is obtained, the tester shall record the leakage rate and void the sampling run.
8.6Sampling Train Operation
8.6.1During the sampling run, maintain an isokinetic sampling rate to within 10 percent of true isokinetic, below 28 l/min (1.0 cfm). Maintain a temperature around the probe of 120 °C ±14 °C (248 ° ±25 °F).
8.6.2For each run, record the data on a data sheet such as the one shown in Figure 2. Be sure to record the initial dry-gas meter reading. Record the dry-gas meter readings at the beginning and end of each sampling time increment, when changes in flow rates are made, before and after each leak-check, and when sampling is halted. Take other readings required by Figure 2 at least once at each sample point during each time increment and additional readings when significant adjustments (20 percent variation in velocity head readings) necessitate additional adjustments in flow rate. Level and zero the manometer. Because the manometer level and zero may drift due to vibrations and temperature changes, make periodic checks during the traverse.
Traverse point number Sampling time(e) min. Vacuummm Hg (in. Hg) Stack temperature (T)°C (°F) Velocity head(ΔP) mm (in) H2O Pressure differential across orifice metermm H2O (in. H2O) Gas sample volumem3 (ft3) Gas sample temperature at dry gas meter Filter holder temperature°C (°F) Temperature of gas leaving condenser or last impinger°C (°F)
Inlet°C (°F) Outlet°C (°F)
Total Avg. Avg.
Average Avg.
8.6.3Clean the stack access ports prior to the test run to eliminate the chance of sampling deposited material. To begin sampling, remove the nozzle cap, verify that the probe heating system are at the specified temperature, and verify that the pitot tube and probe are properly positioned. Position the nozzle at the first traverse point, with the tip pointing directly into the gas stream. Immediately start the pump and adjust the flow to isokinetic conditions. Nomographs, which aid in the rapid adjustment of the isokinetic sampling rate without excessive computations, are available. These nomographs are designed for use when the Type S pitot tube coefficient is 0.84 ±0.02 and the stack gas equivalent density (dry molecular weight) is equal to 29 ±4. APTD-0576 details the procedure for using the nomographs. If the stack gas molecular weight and the pitot tube coefficient are outside the above ranges, do not use the nomographs unless appropriate steps are taken to compensate for the deviations.
8.6.4When the stack is under significant negative pressure (equivalent to the height of the impinger stem), take care to close the coarse-adjust valve before inserting the probe into the stack in order to prevent liquid from backing up through the train. If necessary, a low vacuum on the train may have to be started prior to entering the stack.
8.6.5When the probe is in position, block off the openings around the probe and stack access port to prevent unrepresentative dilution of the gas stream.
8.6.6Traverse the stack cross section, as required by EPA Method 1, 40 CFR part 60, appendix A, being careful not to bump the probe nozzle into the stack walls when sampling near the walls or when removing or inserting the probe through the access port, in order to minimize the chance of extracting deposited material.
8.6.7During the test run, make periodic adjustments to keep the temperature around the probe at the proper levels. Add more ice and, if necessary, salt, to maintain a temperature of <20 °C (68 °F) at the silica gel outlet.
8.6.8A single train shall be used for the entire sampling run, except in cases where simultaneous sampling is required in two or more separate ducts or at two or more different locations within the same duct, or in cases where equipment failure necessitates a change of trains. An additional train or trains may also be used for sampling when the capacity of a single train is exceeded.
8.6.9When two or more trains are used, separate analyses of components from each train shall be performed. If multiple trains have been used because the capacity of a single train would be exceeded, first impingers from each train may be combined, and second impingers from each train may be combined.
8.6.10At the end of the sampling run, turn off the coarse-adjust valve, remove the probe and nozzle from the stack, turn off the pump, record the final dry gas meter reading, and conduct a post-test leak-check. Also, check the pitot lines as described in EPA Method 2, 40 CFR part 60, appendix A. The lines must pass this leak-check in order to validate the velocity-head data.
8.6.11Calculate percent isokineticity (see Method 2) to determine whether the run was valid or another test should be made.
8.7Sample Preservation and Handling
8.7.1Samples from most sources applicable to this method have acceptable holding times using normal handling practices (shipping samples iced, storing in refrigerator at 2 °C until analysis). However, forming section stacks and other sources using waste water sprays may be subject to microbial contamination. For these sources, a biocide (quaternary ammonium compound solution) may be added to collected samples to improve sample stability and method ruggedness.
8.7.2Sample holding time: Samples should be analyzed within 14 days of collection. Samples must be refrigerated/kept cold for the entire period preceding analysis. After the samples have been brought to room temperature for analysis, any analyses needed should be performed on the same day. Repeated cycles of warming the samples to room temperature/refrigerating/rewarming, then analyzing again, etc., have not been investigated in depth to evaluate if analyte levels remain stable for all sources.
8.7.3Additional studies will be performed to evaluate whether longer sample holding times are feasible for this method.
8.8Sample Recovery
8.8.1Preparation:
8.8.1.1Proper cleanup procedure begins as soon as the probe is removed from the stack at the end of the sampling period. Allow the probe to cool. When the probe can be handled safely, wipe off all external particulate matter near the tip of the probe nozzle and place a cap over the tip to prevent losing or gaining particulate matter. Do not cap the probe tightly while the sampling train is cooling because a vacuum will be created, drawing liquid from the impingers back through the sampling train.
8.8.1.2Before moving the sampling train to the cleanup site, remove the probe from the sampling train and cap the open outlet, being careful not to lose any condensate that might be present. Remove the umbilical cord from the last impinger and cap the impinger. If a flexible line is used, let any condensed water or liquid drain into the impingers. Cap off any open impinger inlets and outlets. Ground glass stoppers, Teflon TM caps, or caps of other inert materials may be used to seal all openings.
8.8.1.3Transfer the probe and impinger assembly to an area that is clean and protected from wind so that the chances of contaminating or losing the sample are minimized.
8.8.1.4Inspect the train before and during disassembly, and note any abnormal conditions.
8.8.1.5Save a portion of the washing solution (high purity water) used for cleanup as a blank.
8.8.2Sample Containers:
8.8.2.1Container 1: Probe and Impinger Catches. Using a graduated cylinder, measure to the nearest ml, and record the volume of the solution in the first three impingers. Alternatively, the solution may be weighed to the nearest 0.5 g. Include any condensate in the probe in this determination. Transfer the combined impinger solution from the graduated cylinder into the polyethylene bottle. Taking care that dust on the outside of the probe or other exterior surfaces does not get into the sample, clean all surfaces to which the sample is exposed (including the probe nozzle, probe fitting, probe liner, first three impingers, and impinger connectors) with water. Use less than 400 ml for the entire waste (250 ml would be better, if possible). Add the rinse water to the sample container.
8.8.2.1.1Carefully remove the probe nozzle and rinse the inside surface with water from a wash bottle. Brush with a bristle brush and rinse until the rinse shows no visible particles, after which make a final rinse of the inside surface. Brush and rinse the inside parts of the Swagelok (or equivalent) fitting with water in a similar way.
8.8.2.1.2Rinse the probe liner with water. While squirting the water into the upper end of the probe, tilt and rotate the probe so that all inside surfaces will be wetted with water. Let the water drain from the lower end into the sample container. The tester may use a funnel (glass or polyethylene) to aid in transferring the liquid washes to the container. Follow the rinse with a bristle brush. Hold the probe in an inclined position, and squirt water into the upper end as the probe brush is being pushed with a twisting action through the probe. Hold the sample container underneath the lower end of the probe, and catch any water and particulate matter that is brushed from the probe. Run the brush through the probe three times or more. Rinse the brush with water and quantitatively collect these washings in the sample container. After the brushing, make a final rinse of the probe as describe above.
Note:
Two people should clean the probe in order to minimize sample losses. Between sampling runs, brushes must be kept clean and free from contamination.
8.8.2.1.3Rinse the inside surface of each of the first three impingers (and connecting tubing) three separate times. Use a small portion of water for each rinse, and brush each surface to which the sample is exposed with a bristle brush to ensure recovery of fine particulate matter. Make a final rinse of each surface and of the brush, using water.
8.8.2.1.4After all water washing and particulate matter have been collected in the sample container, tighten the lid so the sample will not leak out when the container is shipped to the laboratory. Mark the height of the fluid level to determine whether leakage occurs during transport. Label the container clearly to identify its contents.
8.8.2.1.5If the first two impingers are to be analyzed separately to check for breakthrough, separate the contents and rinses of the two impingers into individual containers. Care must be taken to avoid physical carryover from the first impinger to the second. Any physical carryover of collected moisture into the second impinger will invalidate a breakthrough assessment.
8.8.2.2Container 2: Sample Blank. Prepare a blank by using a polyethylene container and adding a volume of water equal to the total volume in Container 1. Process the blank in the same manner as Container 1.
8.8.2.3Container 3: Silica Gel. Note the color of the indicating silica gel to determine whether it has been completely spent and make a notation of its condition. The impinger containing the silica gel may be used as a sample transport container with both ends sealed with tightly fitting caps or plugs. Ground-glass stoppers or Teflon TM caps maybe used. The silica gel impinger should then be labeled, covered with aluminum foil, and packaged on ice for transport to the laboratory. If the silica gel is removed from the impinger, the tester may use a funnel to pour the silica gel and a rubber policeman to remove the silica gel from the impinger. It is not necessary to remove the small amount of dust particles that may adhere to the impinger wall and are difficult to remove. Since the gain in weight is to be used for moisture calculations, do not use water or other liquids to transfer the silica gel. If a balance is available in the field, the spent silica gel (or silica gel plus impinger) may be weighed to the nearest 0.5 g.
8.8.2.4Sample containers should be placed in a cooler, cooled by (although not in contact with) ice. Putting sample bottles in Zip-Lock TM bags can aid in maintaining the integrity of the sample labels. Sample containers should be placed vertically to avoid leakage during shipment. Samples should be cooled during shipment so they will be received cold at the laboratory. It is critical that samples be chilled immediately after recovery. If the source is susceptible to microbial contamination from wash water (e.g. forming section stack), add biocide as directed in section 8.2.5.
8.8.2.5A quaternary ammonium compound can be used as a biocide to stabilize samples against microbial degradation following collection. Using the stock quaternary ammonium compound (QAC) solution; add 2.5 ml QAC solution for every 100 ml of recovered sample volume (estimate of volume is satisfactory) immediately after collection. The total volume of QAC solution must be accurately known and recorded, to correct for any dilution caused by the QAC solution addition.
8.8.3Sample Preparation for Analysis 8.8.3.1 The sample should be refrigerated if the analysis will not be performed on the day of sampling. Allow the sample to warm at room temperature for about two hours (if it has been refrigerated) prior to analyzing.
8.8.3.2Analyze the sample by the pararosaniline method, as described in Section 11. If the color-developed sample has an absorbance above the highest standard, a suitable dilution in high purity water should be prepared and analyzed.
9.0Quality Control
9.1Sampling: See EPA Manual 600/4-77-02b for Method 5 quality control.
9.2Analysis: The quality assurance program required for this method includes the analysis of the field and method blanks, and procedure validations. The positive identification and quantitation of formaldehyde are dependent on the integrity of the samples received and the precision and accuracy of the analytical methodology. Quality assurance procedures for this method are designed to monitor the performance of the analytical methodology and to provide the required information to take corrective action if problems are observed in laboratory operations or in field sampling activities.
9.2.1Field Blanks: Field blanks must be submitted with the samples collected at each sampling site. The field blanks include the sample bottles containing aliquots of sample recover water, and water reagent. At a minimum, one complete sampling train will be assembled in the field staging area, taken to the sampling area, and leak-checked at the beginning and end of the testing (or for the same total number of times as the actual sampling train). The probe of the blank train must be heated during the sample test. The train will be recovered as if it were an actual test sample. No gaseous sample will be passed through the blank sampling train.
9.2.2Blank Correction: The field blank formaldehyde concentrations will be subtracted from the appropriate sample formaldehyde concentrations. Blank formaldehyde concentrations above 0.25 µg/ml should be considered suspect, and subtraction from the sample formaldehyde concentrations should be performed in a manner acceptable to the Administrator.
9.2.3Method Blanks: A method blank must be prepared for each set of analytical operations, to evaluate contamination and artifacts that can be derived from glassware, reagents, and sample handling in the laboratory.
10Calibration
10.1Probe Nozzle: Probe nozzles shall be calibrated before their initial use in the field. Using a micrometer, measure the inside diameter of the nozzle to the nearest 0.025 mm (0.001 in). Make measurements at three separate places across the diameter and obtain the average of the measurements. The difference between the high and low numbers shall not exceed 0.1 mm (0.004 in). When the nozzle becomes nicked or corroded, it shall be repaired and calibrated, or replaced with a calibrated nozzle before use. Each nozzle must be permanently and uniquely identified.
10.2Pitot Tube: The Type S pitot tube assembly shall be calibrated according to the procedure outlined in Section 4 of EPA Method 2, or assigned a nominal coefficient of 0.84 if it is not visibly nicked or corroded and if it meets design and intercomponent spacing specifications.
10.3Metering System
10.3.1Before its initial use in the field, the metering system shall be calibrated according to the procedure outlined in APTD-0576. Instead of physically adjusting the dry-gas meter dial readings to correspond to the wet-test meter readings, calibration factors may be used to correct the gas meter dial readings mathematically to the proper values. Before calibrating the metering system, it is suggested that a leak-check be conducted. For metering systems having diaphragm pumps, the normal leak-check procedure will not delete leakages with the pump. For these cases, the following leak-check procedure will apply: Make a ten-minute calibration run at 0.00057 m3/min (0.02 cfm). At the end of the run, take the difference of the measured wet-test and dry-gas meter volumes and divide the difference by 10 to get the leak rate. The leak rate should not exceed 0.00057 m3/min (0.02 cfm).
10.3.2After each field use, check the calibration of the metering system by performing three calibration runs at a single intermediate orifice setting (based on the previous field test). Set the vacuum at the maximum value reached during the test series. To adjust the vacuum, insert a valve between the wet-test meter and the inlet of the metering system. Calculate the average value of the calibration factor. If the calibration has changed by more than 5 percent, recalibrate the meter over the full range of orifice settings, as outlined in APTD-0576.
10.3.3Leak-check of metering system: The portion of the sampling train from the pump to the orifice meter (see Figure 1) should be leak-checked prior to initial use and after each shipment. Leakage after the pump will result in less volume being recorded than is actually sampled. Use the following procedure: Close the main valve on the meter box. Insert a one-hole rubber stopper with rubber tubing attached into the orifice exhaust pipe. Disconnect and vent the low side of the orifice manometer. Close off the low side orifice tap. Pressurize the system to 13-18 cm (5-7 in) water column by blowing into the rubber tubing. Pinch off the tubing and observe the manometer for 1 min. A loss of pressure on the manometer indicates a leak in the meter box. Leaks must be corrected.
Note:
If the dry-gas meter coefficient values obtained before and after a test series differ by >5 percent, either the test series must be voided or calculations for test series must be performed using whichever meter coefficient value (i.e., before or after) gives the lower value of total sample volume.
10.4Probe Heater: The probe heating system must be calibrated before its initial use in the field according to the procedure outlined in APTD-0576. Probes constructed according to APTD-0581 need not be calibrated if the calibration curves in APTD-0576 are used.
10.5Temperature gauges: Use the procedure in section 4.3 of USEPA Method 2 to calibrate in-stack temperature gauges. Dial thermometers such as are used for the dry gas meter and condenser outlet, shall be calibrated against mercury-in-glass thermometers.
10.6Barometer: Adjust the barometer initially and before each test series to agree to within ±2.5 mm Hg (0.1 in Hg) of the mercury barometer. Alternately, if a National Weather Service Station (NWSS) is located at the same altitude above sea level as the test site, the barometric pressure reported by the NWSS may be used.
10.7Balance: Calibrate the balance before each test series, using Class S standard weights. The weights must be within ±0.5 percent of the standards, or the balance must be adjusted to meet these limits.
11.0Procedure for Analysis
The working formaldehyde standards (0.25, 0.50, 1.0, 2.0, and 3.0 µg/ml) are analyzed and a calibration curve is calculated for each day's analysis. The standards should be analyzed first to ensure that the method is working properly prior to analyzing the samples. In addition, a sample of the high-purity water should also be analyzed and used as a “0” formaldehyde standard.
The procedure for analysis of samples and standards is identical: Using the pipet set to 2.50 ml, pipet 2.50 ml of the solution to be analyzed into a polystyrene cuvette. Using the 250 µl pipet, pipet 250 µl of the pararosaniline reagent solution into the cuvette. Seal the top of the cuvette with a Parafilm square and shake at least 30 seconds to ensure the solution in the cuvette is well-mixed. Peel back a corner of the Parafilm so the next reagent can be added. Using the 250 µl pipet, pipet 250 µl of the sodium sulfite reagent solution into the cuvette. Reseal the cuvette with the Parafilm, and again shake for about 30 seconds to mix the solution in the cuvette. Record the time of addition of the sodium sulfite and let the color develop at room temperature for 60 minutes. Set the spectrophotometer to 570 nm and set to read in Absorbance Units. The spectrophotometer should be equipped with a holder for the 1-cm pathlength cuvettes. Place cuvette(s) containing high-purity water in the spectrophotometer and adjust to read 0.000 AU.
After the 60 minutes color development period, read the standard and samples in the spectrophotometer. Record the absorbance reading for each cuvette. The calibration curve is calculated by linear regression, with the formaldehyde concentration as the “x” coordinate of the pair, and the absorbance reading as the “y” coordinate. The procedure is very reproducible, and typically will yield values similar to these for the calibration curve:
Correlation Coefficient: 0.9999
Slope: 0.50
Y-Intercept: 0.090
The formaldehyde concentration of the samples can be found by using the trend-line feature of the calculator or computer program used for the linear regression. For example, the TI-55 calculators use the “X” key (this gives the predicted formaldehyde concentration for the value of the absorbance you key in for the sample). Multiply the formaldehyde concentration from the sample by the dilution factor, if any, for the sample to give the formaldehyde concentration of the original, undiluted, sample (units will be micrograms/ml).
11.1Notes on the Pararosaniline Procedure
11.1.1The pararosaniline method is temperature-sensitive. However, the small fluctuations typical of a laboratory will not significantly affect the results.
11.1.2The calibration curve is linear to beyond 4 “µg/ml” formaldehyde, however, a research-grade spectrophotometer is required to reproducibly read the high absorbance values. Consult your instrument manual to evaluate the capability of the spectrophotometer.
11.1.3The quality of the laboratory water used to prepare standards and make dilutions is critical. It is important that the cautions given in the Reagents section be observed. This procedure allows quantitation of formaldehyde at very low levels, and thus it is imperative to avoid contamination from other sources of formaldehyde and to exercise the degree of care required for trace analyses.
11.1.4The analyst should become familiar with the operation of the Oxford or equivalent pipettors before using them for an analysis. Follow the instructions of the manufacturer; one can pipet water into a tared container on any analytical balance to check pipet accuracy and precision. This will also establish if the proper technique is being used. Always use a new tip for each pipetting operation.
11.1.5This procedure follows the recommendations of ASTM Standard Guide D 3614, reading all solutions versus water in the reference cell. This allows the absorbance of the blank to be tracked on a daily basis. Refer to ASTM D 3614 for more information.
12.0Calculations
Carry out calculations, retaining at least one extra decimal figure beyond that of the acquired data. Round off figures after final calculations.
12.1Calculations of Total Formaldehyde
12.1.1To determine the total formaldehyde in mg, use the following equation if biocide was not used:
Total mg formaldehyde=
Where:
Cd = measured conc. formaldehyde, µg/ml
V = total volume of stack sample, ml
DF = dilution factor
12.1.2To determine the total formaldehyde in mg, use the following equation if biocide was used:
Total mg formaldehyde=
Where:
Cd = measured conc. formaldehyde, µg/ml
V = total volume of stack sample, ml
B = total volume of biocide added to sample, ml
DF = dilution factor
12.2Formaldehyde concentration (mg/m3) in stack gas. Determine the formaldehyde concentration (mg/m3) in the stack gas using the following equation: Formaldehyde concentration (mg/m3) =
Where:
K = 35.31 cu ft/m3 for Vm(std) in English units, or
K = 1.00 m3/m3 for Vm(std) in metric units
Vm(std) = volume of gas sample measured by a dry gas meter, corrected to standard conditions, dscm (dscf)
12.3Average dry gas meter temperature and average orifice pressure drop are obtained from the data sheet.
12.4Dry Gas Volume: Calculate Vm(std) and adjust for leakage, if necessary, using the equation in Section 6.3 of EPA Method 5, 40 CFR part 60, appendix A.
12.5Volume of Water Vapor and Moisture Content: Calculated the volume of water vapor and moisture content from equations 5-2 and 5-3 of EPA Method 5.
13.0Method Performance
The precision of this method is estimated to be better than ±5 percent, expressed as ± the percent relative standard deviation.
14.0Pollution Prevention [Reserved]
15.0Waste Management [Reserved]
16.0References
R.R. Miksch, et al., Analytical Chemistry, November 1981, 53 pp. 2118-2123.
J.F. Walker, Formaldehyde, Third Edition, 1964.
US EPA 40 CFR, part 60, Appendix A, Test Methods 1-5
Method 318—Extractive FTIR Method for the Measurement of Emissions From the Mineral Wool and Wool Fiberglass Industries
1.0Scope and Application
This method has been validated and approved for mineral wool and wool fiberglass sources. This method may not be applied to other source categories without validation and approval by the Administrator according to the procedures in Test Method 301, 40 CFR part 63, appendix A. For sources seeking to apply FTIR to other source categories, Test Method 320 (40 CFR part 63, appendix A) may be utilized.
1.1Scope. The analytes measured by this method and their CAS numbers are:
Carbon Monoxide630-08-0
Carbonyl Sulfide463-58-1
Formaldehyde50-00-0
Methanol1455-13-6
Phenol108-95-2
1.2Applicability
1.2.1This method is applicable for the determination of formaldehyde, phenol, methanol, carbonyl sulfide (COS) and carbon monoxide (CO) concentrations in controlled and uncontrolled emissions from manufacturing processes using phenolic resins. The compounds are analyzed in the mid-infrared spectral region (about 400 to 4000 cm−1 or 25 to 2.5 µm). Suggested analytical regions are given below (Table 1). Slight deviations from these recommended regions may be necessary due to variations in moisture content and ammonia concentration from source to source.
Table 1—Example Analytical Regions
Compound Analytical region (cm−1)FLm − FUm Potential interferants
a Suggested analytical regions assume about 15 percent moisture and CO2, and that COS and CO have about the same absorbance (in the range of 10 to 50 ppm). If CO and COS are hundreds of ppm or higher, then CO2 and moisture interference is reduced. If CO or COS is present at high concentration and the other at low concentration, then a shorter cell pathlength may be necessary to measure the high concentration component.
Formaldehyde 2840.93−2679.83 Water, Methane.
Phenol 1231.32−1131.47 Water, Ammonia, Methane.
Methanol 1041.56−1019.95 Water, Ammonia.
COS a 2028.4−2091.9 Water, CO2 CO.
CO a 2092.1−2191.8 Water, CO2, COS.
1.2.2This method does not apply when: (a) Polymerization of formaldehyde occurs, (b) moisture condenses in either the sampling system or the instrumentation, and (c) when moisture content of the gas stream is so high relative to the analyte concentrations that it causes severe spectral interference.
1.3Method Range and Sensitivity
1.3.1The analytical range is a function of instrumental design and composition of the gas stream. Theoretical detection limits depend, in part, on (a) the absorption coefficient of the compound in the analytical frequency region, (b) the spectral resolution, (c) interferometer sampling time, (d) detector sensitivity and response, and (e) absorption pathlength.
1.3.2Practically, there is no upper limit to the range. The practical lower detection limit is usually higher than the theoretical value, and depends on (a) moisture content of the flue gas, (b) presence of interferants, and (c) losses in the sampling system. In general, a 22 meter pathlength cell in a suitable sampling system can achieve practical detection limits of 1.5 ppm for three compounds (formaldehyde, phenol, and methanol) at moisture levels up to 15 percent by volume. Sources with uncontrolled emissions of CO and COS may require a 4 meter pathlength cell due to high concentration levels. For these two compounds, make sure absorbance of highest concentration component is <1.0.
1.4Data Quality Objectives
1.4.1In designing or configuring the system, the analyst first sets the data quality objectives, i.e., the desired lower detection limit (DLi) and the desired analytical uncertainty (AUi) for each compound. The instrumental parameters (factors b, c, d, and e in Section 1.3.1) are then chosen to meet these requirements, using Appendix D of the FTIR Protocol.
1.4.2Data quality for each application is determined, in part, by measuring the RMS (Root Mean Square) noise level in each analytical spectral region (Appendix C of the FTIR Protocol). The RMS noise is defined as the RMSD (Root Mean Square Deviation) of the absorbance values in an analytical region from the mean absorbance value of the region. Appendix D of the FTIR Protocol defines the MAUim (minimum analyte uncertainty of the ith analyte in the mth analytical region). The MAU is the minimum analyte concentration for which the analytical uncertainty limit (AUi) can be maintained: if the measured analyte concentration is less than MAUi, then data quality is unacceptable. Table 2 gives some example DL and AU values along with calculated areas and MAU values using the protocol procedures.
Table 2—Example Pre-Test Protocol Calculations
Protocol value Form Phenol Methanol Protocolappendix
a Concentration units are: ppm concentration of the reference sample (ASC), times the path length of the FTIR cell used when the reference spectrum was measured (meters), divided by the absolute temperature of the reference sample in Kelvin (K), or (ppm-meters)/K.
Reference concentration a (ppm-meters)/K 3.016 3.017 5.064
Reference Band Area 8.2544 16.6417 4.9416 B
DL (ppm-meters)/K 0.1117 0.1117 0.1117 B
AU 0.2 0.2 0.2 B
CL 0.02234 0.02234 0.02234 B
FL 2679.83 1131.47 1019.95 B
FU 2840.93 1231.32 1041.56 B
FC 2760.38 1181.395 1030.755 B
AAI (ppm-meters)/K 0.18440 0.01201 0.00132 B
RMSD 2.28E-03 1.21E-03 1.07E-03 C
MAU (ppm-meters)/K 4.45E-02 7.26E-03 4.68E-03 D
MAU (ppm at 22) 0.0797 0.0130 0.0084 D
2.0Summary of Method
2.1Principle
2.1.1Molecules are composed of chemically bonded atoms, which are in constant motion. The atomic motions result in bond deformations (bond stretching and bond-angle bending). The number of fundamental (or independent) vibrational motions depends on the number of atoms (N) in the molecule. At typical testing temperatures, most molecules are in the ground-state vibrational state for most of their fundamental vibrational motions. A molecule can undergo a transition from its ground state (for a particular vibration) to the first excited state by absorbing a quantum of light at a frequency characteristic of the molecule and the molecular motion. Molecules also undergo rotational transitions by absorbing energies in the far-infrared or microwave spectral regions. Rotational transition absorbencies are superimposed on the vibrational absorbencies to give a characteristic shape to each rotational-vibrational absorbance “band.”
2.1.2Most molecules exhibit more than one absorbance band in several frequency regions to produce an infrared spectrum (a characteristic pattern of bands or a “fingerprint”) that is unique to each molecule. The infrared spectrum of a molecule depends on its structure (bond lengths, bond angles, bond strengths, and atomic masses). Even small differences in structure can produce significantly different spectra.
2.1.3Spectral band intensities vary with the concentration of the absorbing compound. Within constraints, the relationship between absorbance and sample concentration is linear. Sample spectra are compared to reference spectra to determine the species and their concentrations.
2.2Sampling and Analysis
2.2.1Flue gas is continuously extracted from the source, and the gas or a portion of the gas is conveyed to the FTIR gas cell, where a spectrum of the flue gas is recorded. Absorbance band intensities are related to sample concentrations by Beer's Law.
Where:
An = absorbance of the ith component at the given frequency, ν.
a = absorption coefficient of the ith component at the frequency, ν.
b = path length of the cell.
c = concentration of the ith compound in the sample at frequency ν.
2.2.2After identifying a compound from the infrared spectrum, its concentration is determined by comparing band intensities in the sample spectrum to band intensities in “reference spectra” of the formaldehyde, phenol, methanol, COS and CO. These reference spectra are available in a permanent soft copy from the EPA spectral library on the EMTIC bulletin board. The source may also prepare reference spectra according to Section 4.5 of the FTIR Protocol.
Note:
Reference spectra not prepared according to the FTIR Protocol are not acceptable for use in this test method. Documentation detailing the FTIR Protocol steps used in preparing any non-EPA reference spectra shall be included in each test report submitted by the source.
2.3Operator Requirements. The analyst must have some knowledge of source sampling and of infrared spectral patterns to operate the sampling system and to choose a suitable instrument configuration. The analyst should also understand FTIR instrument operation well enough to choose an instrument configuration consistent with the data quality objectives.
3.0Definitions
See Appendix A of the FTIR Protocol.
4.0Interferences
4.1Analytical (or Spectral) Interferences. Water vapor. High concentrations of ammonia (hundreds of ppm) may interfere with the analysis of low concentrations of methanol (1 to 5 ppm). For CO, carbon dioxide and water may be interferants. In cases where COS levels are low relative to CO levels, CO and water may be interferants.
4.2Sampling System Interferences. Water, if it condenses, and ammonia, which reacts with formaldehyde.
5.0Safety
5.1Formaldehyde is a suspected carcinogen; therefore, exposure to this compound must be limited. Proper monitoring and safety precautions must be practiced in any atmosphere with potentially high concentrations of CO.
5.2This method may involve sampling at locations having high positive or negative pressures, high temperatures, elevated heights, high concentrations of hazardous or toxic pollutants, or other diverse sampling conditions. It is the responsibility of the tester(s) to ensure proper safety and health practices, and to determine the applicability of regulatory limitations before performing this test method.
6.0Equipment and Supplies
The equipment and supplies are based on the schematic of a sampling train shown in Figure 1. Either the evacuated or purged sampling technique may be used with this sampling train. Alternatives may be used, provided that the data quality objectives of this method are met.
6.1Sampling Probe. Glass, stainless steel, or other appropriate material of sufficient length and physical integrity to sustain heating, prevent adsorption of analytes, and to reach gas sampling point.
6.2Particulate Filters. A glass wool plug (optional) inserted at the probe tip (for large particulate removal) and a filter rated at 1-micron (e.g., Balston TM) for fine particulate removal, placed immediately after the heated probe.
6.3Sampling Line/Heating System. Heated (maintained at 250 ±25 degrees F) stainless steel, Teflon TM, or other inert material that does not adsorb the analytes, to transport the sample to analytical system.
6.4Stainless Steel Tubing. Type 316, e.g., 3/8 in. diameter, and appropriate length for heated connections.
6.5Gas Regulators. Appropriate for individual gas cylinders.
6.6Teflon TM Tubing. Diameter (e.g., 3/8 in.) and length suitable to connect cylinder regulators.
6.7Sample Pump. A leak-free pump (e.g., KNF TM), with by-pass valve, capable of pulling sample through entire sampling system at a rate of about 10 to 20 L/min. If placed before the analytical system, heat the pump and use a pump fabricated from materials non-reactive to the target pollutants. If the pump is located after the instrument, systematically record the sample pressure in the gas cell.
6.8Gas Sample Manifold. A heated manifold that diverts part of the sample stream to the analyzer, and the rest to the by-pass discharge vent or other analytical instrumentation.
6.9Rotameter. A calibrated 0 to 20 L/min range rotameter.
6.10FTIR Analytical System. Spectrometer and detector, capable of measuring formaldehyde, phenol, methanol, COS and CO to the predetermined minimum detectable level. The system shall include a personal computer with compatible software that provides real-time updates of the spectral profile during sample collection and spectral collection.
6.11FTIR Cell Pump. Required for the evacuated sampling technique, capable of evacuating the FTIR cell volume within 2 minutes. The FTIR cell pump should allow the operator to obtain at least 8 sample spectra in 1 hour.
6.12Absolute Pressure Gauge. Heatable and capable of measuring pressure from 0 to 1000 mmHg to within ±2.5 mmHg (e.g., Baratron TM).
6.13Temperature Gauge. Capable of measuring the cell temperature to within ±2 °C.
7.0Reagents and Standards
7.1Ethylene (Calibration Transfer Standard). Obtain NIST traceable (or Protocol) cylinder gas.
7.2Nitrogen. Ultra high purity (UHP) grade.
7.3Reference Spectra. Obtain reference spectra for the target pollutants at concentrations that bracket (in ppm-meter/K) the emission source levels. Also, obtain reference spectra for SF6 and ethylene. Suitable concentrations are 0.0112 to 0.112 (ppm-meter)/K for SF6 and 5.61 (ppm-meter)/K or less for ethylene. The reference spectra shall meet the criteria for acceptance outlined in Section 2.2.2. The optical density (ppm-meters/K) of the reference spectrum must match the optical density of the sample spectrum within (less than) 25 percent.
8.0Sample Collection, Preservation, and Storage
Sampling should be performed in the following sequence: Collect background, collect CTS spectrum, collect samples, collect post-test CTS spectrum, verify that two copies of all data were stored on separate computer media.
8.1Pretest Preparations and Evaluations. Using the procedure in Section 4.0 of the FTIR Protocol, determine the optimum sampling system configuration for sampling the target pollutants. Table 2 gives some example values for AU, DL, and MAU. Based on a study (Reference 1), an FTIR system using 1 cm−1 resolution, 22 meter path length, and a broad band MCT detector was suitable for meeting the requirements in Table 2. Other factors that must be determined are:
a. Test requirements: AUi, CMAXi, DLi, OFUi, and tAN for each.
b. Interferants: See Table 1.
c. Sampling system: LS′, Pmin, PS′, TS′, tSS, VSS; fractional error, MIL.
d. Analytical regions: 1 through Nm, FLm, FCm, and FUm, plus interferants, FFUm, FFLm, wavenumber range FNU to FNL. See Tables 1 and 2.
8.1.1If necessary, sample and acquire an initial spectrum. Then determine the proper operational pathlength of the instrument to obtain non-saturated absorbances of the target analytes.
8.1.2Set up the sampling train as shown in Figure 1.
8.2Sampling System Leak-check. Leak-check from the probe tip to pump outlet as follows: Connect a 0- to 250-mL/min rate meter (rotameter or bubble meter) to the outlet of the pump. Close off the inlet to the probe, and note the leakage rate. The leakage rate shall be ≤200 mL/min.
8.3Analytical System Leak-check.
8.3.1For the evacuated sample technique, close the valve to the FTIR cell, and evacuate the absorption cell to the minimum absolute pressure Pmin. Close the valve to the pump, and determine the change in pressure ΔPv after 2 minutes.
8.3.2For both the evacuated sample and purging techniques, pressurize the system to about 100 mmHg above atmospheric pressure. Isolate the pump and determine the change in pressure ΔPp after 2 minutes.
8.3.3Measure the barometric pressure, Pb in mmHg.
8.3.4Determine the percent leak volume %VL for the signal integration time tSS and for ΔPmax, i.e., the larger of ΔPv or ΔPp, as follows:
Where:
50 = 100% divided by the leak-check time of 2 minutes.
8.3.5Leak volumes in excess of 4 percent of the sample system volume VSS are unacceptable.
8.4Background Spectrum. Evacuate the gas cell to ≤5 mmHg, and fill with dry nitrogen gas to ambient pressure. Verify that no significant amounts of absorbing species (for example water vapor and CO2) are present. Collect a background spectrum, using a signal averaging period equal to or greater than the averaging period for the sample spectra. Assign a unique file name to the background spectrum. Store the spectra of the background interferogram and processed single-beam background spectrum on two separate computer media (one is used as the back-up). If continuous sampling will be used during sample collection, collect the background spectrum with nitrogen gas flowing through the cell at the same pressure and temperature as will be used during sampling.
8.5Pre-Test Calibration Transfer Standard. Evacuate the gas cell to ≤5 mmHg absolute pressure, and fill the FTIR cell to atmospheric pressure with the CTS gas. Or, purge the cell with 10 cell volumes of CTS gas. Record the spectrum. If continuous sampling will be used during sample collection, collect the CTS spectrum with CTS gas flowing through the cell at the same pressure and temperature as will be used during sampling.
8.6Samples
8.6.1Evacuated Samples. Evacuate the absorbance cell to ≤5 mmHg absolute pressure. Fill the cell with flue gas to ambient pressure and record the spectrum. Before taking the next sample, evacuate the cell until no further evidence of absorption exists. Repeat this procedure to collect at least 8 separate spectra (samples) in 1 hour.
8.6.2Purge Sampling. Purge the FTIR cell with 10 cell volumes of flue gas and at least for about 10 minutes. Discontinue the gas cell purge, isolate the cell, and record the sample spectrum and the pressure. Before taking the next sample, purge the cell with 10 cell volumes of flue gas.
8.6.3Continuous Sampling. Spectra can be collected continuously while the FTIR cell is being purged. The sample integration time, tss, the sample flow rate through the FTIR gas cell, and the total run time must be chosen so that the collected data consist of at least 10 spectra with each spectrum being of a separate cell volume of flue gas. More spectra can be collected over the run time and the total run time (and number of spectra) can be extended as well.
8.7Sampling QA, Data Storage and Reporting
8.7.1Sample integration times should be sufficient to achieve the required signal-to-noise ratios. Obtain an absorbance spectrum by filling the cell with nitrogen. Measure the RMSD in each analytical region in this absorbance spectrum. Verify that the number of scans is sufficient to achieve the target MAU (Table 2).
8.7.2Identify all sample spectra with unique file names.
8.7.3Store on two separate computer media a copy of sample interferograms and processed spectra. The data shall be available to the Administrator on request for the length of time specified in the applicable regulation.
8.7.4For each sample spectrum, document the sampling conditions, the sampling time (while the cell was being filled), the time the spectrum was recorded, the instrumental conditions (path length, temperature, pressure, resolution, integration time), and the spectral file name. Keep a hard copy of these data sheets.
8.8Signal Transmittance. While sampling, monitor the signal transmittance through the instrumental system. If signal transmittance (relative to the background) drops below 95 percent in any spectral region where the sample does not absorb infrared energy, obtain a new background spectrum.
8.9Post-run CTS. After each sampling run, record another CTS spectrum.
8.10Post-test QA
8.10.1Inspect the sample spectra immediately after the run to verify that the gas matrix composition was close to the expected (assumed) gas matrix.
8.10.2Verify that the sampling and instrumental parameters were appropriate for the conditions encountered. For example, if the moisture is much greater than anticipated, it will be necessary to use a shorter path length or dilute the sample.
8.10.3Compare the pre and post-run CTS spectra. They shall agree to within −5 percent. See FTIR Protocol, Appendix E.
9.0Quality Control
Follow the quality assurance procedures in the method, including the analysis of pre and post-run calibration transfer standards (Sections 8.5 and 8.9) and the post-test quality assurance procedures in Section 8.10.
10.0Calibration and Standardization
10.1Signal-to-Noise Ratio (S/N). The S/N shall be sufficient to meet the MAU in each analytical region.
10.2Absorbance Pathlength. Verify the absorbance path length by comparing CTS spectra to reference spectra of the calibration gas(es). See FTIR Protocol, Appendix E.
10.3Instrument Resolution. Measure the line width of appropriate CTS band(s) and compare to reference CTS spectra to verify instrumental resolution.
10.4Apodization Function. Choose appropriate apodization function. Determine any appropriate mathematical transformations that are required to correct instrumental errors by measuring the CTS. Any mathematical transformations must be documented and reproducible.
10.5FTIR Cell Volume. Evacuate the cell to ≤5 mmHg. Measure the initial absolute temperature (Ti) and absolute pressure (Pi). Connect a wet test meter (or a calibrated dry gas meter), and slowly draw room air into the cell. Measure the meter volume (Vm), meter absolute temperature (Tm), and meter absolute pressure (Pm), and the cell final absolute temperature (Tf) and absolute pressure (Pf). Calculate the FTIR cell volume Vss, including that of the connecting tubing, as follows:
As an alternative to the wet test meter/calibrated dry gas meter procedure, measure the inside dimensions of the cell cylinder and calculate its volume.
11.0Procedure
Refer to Sections 4.6-4.11, Sections 5, 6, and 7, and the appendices of the FTIR Protocol.
12.0Data Analysis and Calculations
a. Data analysis is performed using appropriate reference spectra whose concentrations can be verified using CTS spectra. Various analytical programs are available to relate sample absorbance to a concentration standard. Calculated concentrations should be verified by analyzing spectral baselines after mathematically subtracting scaled reference spectra from the sample spectra. A full description of the data analysis and calculations may be found in the FTIR Protocol (Sections 4.0, 5.0, 6.0 and appendices).
b. Correct the calculated concentrations in sample spectra for differences in absorption pathlength between the reference and sample spectra by:
Where:
Ccorr = The pathlength corrected concentration.
Ccalc = The initial calculated concentration (output of the Multicomp program designed for the compound).
Lr = The pathlength associated with the reference spectra.
Ls = The pathlength associated with the sample spectra.
Ts = The absolute temperature (K) of the sample gas.
Tr = The absolute gas temperature (K) at which reference spectra were recorded.
13.0Reporting and Recordkeeping
All interferograms used in determining source concentration shall be stored for the period of time required in the applicable regulation. The Administrator has the option of requesting the interferograms recorded during the test in electronic form as part of the test report.
14.0Method Performance
Refer to the FTIR Protocol.
15.0Pollution Prevention [Reserved]
16.0Waste Management
Laboratory standards prepared from the formaldehyde and phenol are handled according to the instructions in the materials safety data sheets (MSDS).
17.0References
(1) “Field Validation Test Using Fourier Transform Infrared (FTIR) Spectrometry To Measure Formaldehyde, Phenol and Methanol at a Wool Fiberglass Production Facility.” Draft. U.S. Environmental Protection Agency Report, Entropy, Inc., EPA Contract No. 68D20163, Work Assignment I-32, December 1994 (docket item II-A-13).
(2) “Method 301—Field Validation of Pollutant Measurement Methods from Various Waste Media,” 40 CFR part 63, appendix A.
Method 319—Determination of Filtration Efficiency for Paint Overspray Arrestors
1.0Scope and Application
1.1This method applies to the determination of the initial, particle size dependent, filtration efficiency for paint arrestors over the particle diameter range from 0.3 to 10 µm. The method applies to single and multiple stage paint arrestors or paint arrestor media. The method is applicable to efficiency determinations from 0 to 99 percent. Two test aerosols are used—one liquid phase and one solid phase. Oleic acid, a low-volatility liquid (CAS Number 112-80-1), is used to simulate the behavior of wet paint overspray. The solid-phase aerosol is potassium chloride salt (KCl, CAS Number 7447-40-7) and is used to simulate the behavior of a dry overspray. The method is limited to determination of the initial, clean filtration efficiency of the arrestor. Changes in efficiency (either increase or decrease) due to the accumulation of paint overspray on and within the arrestor are not evaluated.
1.2Efficiency is defined as 1—Penetration (e.g., 70 percent efficiency is equal to 0.30 penetration). Penetration is based on the ratio of the downstream particle concentration to the upstream concentration. It is often more useful, from a mathematical or statistical point of view, to discuss the upstream and downstream counts in terms of penetration rather than the derived efficiency value. Thus, this document uses both penetration and efficiency as appropriate.
1.3For a paint arrestor system or subsystem which has been tested by this method, adding additional filtration devices to the system or subsystem shall be assumed to result in an efficiency of at least that of the original system without the requirement for additional testing. (For example, if the final stage of a three-stage paint arrestor system has been tested by itself, then the addition of the other two stages shall be assumed to maintain, as a minimum, the filtration efficiency provided by the final stage alone. Thus, in this example, if the final stage has been shown to meet the filtration requirements of Table 1 of § 63.745 of subpart GG, then the final stage in combination with any additional paint arrestor stages also passes the filtration requirements.)
2.0Summary of Method
2.1This method applies to the determination of the fractional (i.e., particle-size dependent) aerosol penetration of several types of paint arrestors. Fractional penetration is computed from aerosol concentrations measured upstream and downstream of an arrestor installed in a laboratory test rig. The aerosol concentrations upstream and downstream of the arrestors are measured with an aerosol analyzer that simultaneously counts and sizes the particles in the aerosol stream. The aerosol analyzer covers the particle diameter size range from 0.3 to 10 µm in a minimum of 12 contiguous sizing channels. Each sizing channel covers a narrow range of particle diameters. For example, Channel 1 may cover from 0.3 to 0.4 µm, Channel 2 from 0.4 to 0.5 µm, * * * By taking the ratio of the downstream to upstream counts on a channel by channel basis, the penetration is computed for each of the sizing channels.
2.2The upstream and downstream aerosol measurements are made while injecting the test aerosol into the air stream upstream of the arrestor (ambient aerosol is removed with HEPA filters on the inlet of the test rig). This test aerosol spans the particle size range from 0.3 to 10 µm and provides sufficient upstream concentration in each of the optical particle counter (OPC) sizing channels to allow accurate calculation of penetration, down to penetrations of approximately 0.01 (i.e., 1 percent penetration; 99 percent efficiency). Results are presented as a graph and a data table showing the aerodynamic particle diameter and the corresponding fractional efficiency.
3.0Definitions
Aerodynamic Diameter—diameter of a unit density sphere having the same aerodynamic properties as the particle in question.
Efficiency is defined as equal to 1—Penetration.
Optical Particle Counter (OPC)—an instrument that counts particles by size using light scattering. An OPC gives particle diameters based on size, index of refraction, and shape.
Penetration—the fraction of the aerosol that penetrates the filter at a given particle diameter. Penetration equals the downstream concentration divided by the upstream concentration.
4.0Interferences
4.1The influence of the known interferences (particle losses) are negated by correction of the data using blanks.
5.0Safety
5.1There are no specific safety precautions for this method above those of good laboratory practice. This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this method to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
6.0Equipment and Supplies
6.1Test Facility. A schematic diagram of a test duct used in the development of the method is shown in Figure 319-1.
6.1.1The test section, paint spray section, and attached transitions are constructed of stainless and galvanized steel. The upstream and downstream ducting is 20 cm diameter polyvinyl chloride (PVC). The upstream transition provides a 7 ° angle of expansion to provide a uniform air flow distribution to the paint arrestors. Aerosol concentration is measured upstream and downstream of the test section to obtain the challenge and penetrating aerosol concentrations, respectively. Because the downstream ducting runs back under the test section, the challenge and penetrating aerosol taps are located physically near each other, thereby facilitating aerosol sampling and reducing sample-line length. The inlet nozzles of the upstream and downstream aerosol probes are designed to yield isokinetic sampling conditions.
6.1.2The configuration and dimensions of the test duct can deviate from those of Figure 319-1 provided that the following key elements are maintained: the test duct must meet the criteria specified in Table 319-1; the inlet air is HEPA filtered; the blower is on the upstream side of the duct thereby creating a positive pressure in the duct relative to the surrounding room; the challenge air has a temperature between 50 ° and 100 °F and a relative humidity of less than 65 percent; the angle of the upstream transition (if used) to the paint arrestor must not exceed 7 °; the angle of the downstream transition (if used) from the paint arrestor must not exceed 30 °; the test duct must provide a means for mixing the challenge aerosol with the upstream flow (in lieu of any mixing device, a duct length of 15 duct diameters fulfills this requirement); the test duct must provide a means for mixing any penetrating aerosol with the downstream flow (in lieu of any mixing device, a duct length of 15 duct diameters fulfills this requirement); the test section must provide a secure and leak-free mounting for single and multiple stage arrestors; and the test duct may utilize a 180 ° bend in the downstream duct.
Table 319-1—QC Control Limits
Frequency and description Control limits
OPC zero count Each Test. OPC samples HEPA-filtered air <50 counts per minute.
OPC sizing accuracy check Daily. Sample aerosolized PSL spheres Peak of distribution should be in correct OPC channel.
Minimum counts per channel for challenge aerosol Each Test Minimum total of 500 particle counts per channel.
Maximum particle concentration Each Test. Needed to ensure OPC is not overloaded <10% of manufacturer's claimed upper limit corresponding to a 10% count error.
Standard Deviation of Penetration Computed for each test based on the CV of the upstream and downstream counts <0.10 for 0.3 to 3 µm diameter.<0.30 for >3 µm diameter.
0% Penetration Monthly <0.01.
100% Penetration—KCl Triplicate tests performed immediately before, during, or after triplicate arrestor tests 0.3 to 1 µm: 0.90 to 1.10.1 to 3 µm: 0.75 to 1.25. 3 to 10 µm: 0.50 to 1.50.
100% Penetration—Oleic Acid Triplicate tests performed immediately before, during, or after triplicate arrestor tests 0.3 to 1 µm: 0.90 to 1.10.1 to 3 µm: 0.75 to 1.25. 3 to 10 µm: 0.50 to 1.50.
6.2Aerosol Generator. The aerosol generator is used to produce a stable aerosol covering the particle size range from 0.3 to 10 µm diameter. The generator used in the development of this method consists of an air atomizing nozzle positioned at the top of a 0.30-m (12-in.) diameter, 1.3-m (51-in.) tall, acrylic, transparent, spray tower. This tower allows larger sized particles, which would otherwise foul the test duct and sample lines, to fall out of the aerosol. It also adds drying air to ensure that the KCl droplets dry to solid salt particles. After generation, the aerosol passes through an aerosol neutralizer (Kr85 radioactive source) to neutralize any electrostatic charge on the aerosol (electrostatic charge is an unavoidable consequence of most aerosol generation methods). To improve the mixing of the aerosol with the air stream, the aerosol is injected counter to the airflow. Generators of other designs may be used, but they must produce a stable aerosol concentration over the 0.3 to 10 µm diameter size range; provide a means of ensuring the complete drying of the KCl aerosol; and utilize a charge neutralizer to neutralize any electrostatic charge on the aerosol. The resultant challenge aerosol must meet the minimum count per channel and maximum concentration criteria of Table 319-1.
6.3Installation of Paint Arrestor. The paint arrestor is to be installed in the test duct in a manner that precludes air bypassing the arrestor. Since arrestor media are often sold unmounted, a mounting frame may be used to provide back support for the media in addition to sealing it into the duct. The mounting frame for 20 in.×20 in. arrestors will have minimum open internal dimensions of 18 in. square. Mounting frames for 24 in.×24 in. arrestors will have minimum open internal dimensions of 22 in. square. The open internal dimensions of the mounting frame shall not be less than 75 percent of the approach duct dimensions.
6.4Optical Particle Counter. The upstream and downstream aerosol concentrations are measured with a high-resolution optical particle counter (OPC). To ensure comparability of test results, the OPC shall utilize an optical design based on wide-angle light scattering and provided a minimum of 12 contiguous particle sizing channels from 0.3 to 10 µm diameter (based on response to PSL) where, for each channel, the ratio of the diameter corresponding to the upper channel bound to the lower channel bound must not exceed 1.5.
6.5Aerosol Sampling System. The upstream and downstream sample lines must be made of rigid electrically-grounded metallic tubing having a smooth inside surface, and they must be rigidly secured to prevent movement during testing. The upstream and downstream sample lines are to be nominally identical in geometry. The use of a short length (100 mm maximum) of straight flexible tubing to make the final connection to the OPC is acceptable. The inlet nozzles of the upstream and downstream probes must be sharp-edged and of appropriate entrance diameter to maintain isokinetic sampling within 20 percent of the air velocity.
6.5.1The sampling system may be designed to acquire the upstream and downstream samples using (a) sequential upstream-downstream sampling with a single OPC, (b) simultaneous upstream and downstream sampling with two OPC's, or (c) sequential upstream-downstream sampling with two OPC's.
6.5.2When two particle counters are used to acquire the upstream and downstream counts, they must be closely matched in flowrate and optical design.
6.6Airflow Monitor. The volumetric airflow through the system shall be measured with a calibrated orifice plate, flow nozzle, or laminar flow element. The measurement device must have an accuracy of 5 percent or better.
7.0Reagents and Standards
7.1The liquid test aerosol is reagent grade, 98 percent pure, oleic acid (Table 319-2). The solid test aerosol is KCl aerosolized from a solution of KCl in water. In addition to the test aerosol, a calibration aerosol of monodisperse polystyrene latex (PSL) spheres is used to verify the calibration of the OPC.
Table 319-2—Properties of the Test and Calibration Aerosols
Refractive index Density,g/cm 3 Shape
Oleic Acid (liquid-phase challenge aerosol) 1.46 nonabsorbing 0.89 Spherical.
KCl (solid-phase challenge aerosol) 1.49 1.98 Cubic or agglomerated cubes.
PSL (calibration aerosol) 1.59 nonabsorbing 1.05 Spherical.
8.0Sample Collection, Preservation, and Storage
8.1In this test, all sampling occurs in real-time, thus no samples are collected that require preservation or storage during the test. The paint arrestors are shipped and stored to avoid structural damage or soiling. Each arrestor may be shipped in its original box from the manufacturer or similar cardboard box. Arrestors are stored at the test site in a location that keeps them clean and dry. Each arrestor is clearly labeled for tracking purposes.
9.0Quality Control
9.1Table 319-1 lists the QC control limits.
9.2The standard deviation (σ) of the penetration (P) for a given test at each of the 15 OPC sizing channels is computed from the coefficient of variation (CV, the standard deviation divided by the mean) of the upstream and downstream measurements as:
For a properly operating system, the standard deviation of the penetration is < 0.10 at particle diameters from 0.3 to 3 µm and less than 0.30 at diameters > 3 µm.
9.3Data Quality Objectives (DQO).
9.3.1Fractional Penetration. From the triplicate tests of each paint arrestor model, the standard deviation for the penetration measurements at each particle size (i.e., for each sizing channel of the OPC) is computed as:
where Pi represents an individual penetration measurement, and P the average of the 3 (n = 3) individual measurements.
9.3.2Bias of the fractional penetration values is determined from triplicate no-filter and HEPA filter tests. These tests determine the measurement bias at 100 percent penetration and 0 percent penetration, respectively.
9.3.3PSL-Equivalent Light Scattering Diameter. The precision and bias of the OPC sizing determination are based on sampling a known diameter of PSL and noting whether the particle counts peak in the correct channel of the OPC. This is a pass/fail measurement with no calculations involved.
9.3.4Airflow. The precision of the measurement must be within 5 percent of the set point.
10.0Calibration and Standardization
10.1Optical Particle Counter. The OPC must have an up-to-date factory calibration. Check the OPC zero at the beginning and end of each test by sampling HEPA-filtered air. Verify the sizing accuracy on a daily basis (for days when tests are performed) with 1-size PSL spheres.
10.2Airflow Measurement. Airflow measurement devices must have an accuracy of 5 percent or better. Manometers used in conjunction with the orifice plate must be inspected prior to use for proper level, zero, and mechanical integrity. Tubing connections to the manometer must be free from kinks and have secure connections.
10.3Pressure Drop. Measure pressure drop across the paint arrestor with an inclined manometer readable to within 0.01 in. H2O. Prior to use, the level and zero of the manometer, and all tubing connections, must be inspected and adjusted as needed.
11.0Procedure
11.1Filtration Efficiency. For both the oleic acid and KCl challenges, this procedure is performed in triplicate using a new arrestor for each test.
11.1.1General Information and Test Duct Preparation
11.1.1.1Use the “Test Run Sheet” form (Figure 319-2) to record the test information.
Run Sheet
Part 1. General Information
Date and Time:
Test Operator:
Test #:
Paint Arrestor:
Brand/Model
Arrestor Assigned ID #
Condition of arrestor (i.e., is there any damage? Must be new condition to proceed):
Manometer zero and level confirmed?
Part 2. Clean Efficiency Test
Date and Time:
Optical Particle Counter:
20 min. warm up
Zero count (< 50 counts/min)
Daily PSL check
PSL Diam: ___ µm
File name for OPC data:
Test Conditions:
Air Flow: ___
Temp & RH: Temp ___ °F RH ___ %
Atm. Pressure: ___in. Hg
(From mercury barometer)
Aerosol Generator: (record all operating parameters)
Test Aerosol:
(Oleic acid or KCl)
Arrestor:
Pressure drop: at start ___ in. H2O
at end ___ in. H2O
Condition of arrestor at end of test (note any physical deterioration):
Figure 319-2. Test Run Sheet
Other report formats which contain the same information are acceptable.
11.1.1.2Record the date, time, test operator, Test #, paint arrestor brand/model and its assigned ID number. For tests with no arrestor, record none.
11.1.1.3Ensure that the arrestor is undamaged and is in “new” condition.
11.1.1.4Mount the arrestor in the appropriate frame. Inspect for any airflow leak paths.
11.1.1.5Install frame-mounted arrestor in the test duct. Examine the installed arrestor to verify that it is sealed in the duct. For tests with no arrestor, install the empty frame.
11.1.1.6Visually confirm the manometer zero and level. Adjust as needed.
11.1.2Clean Efficiency Test.
11.1.2.1Record the date and time upon beginning this section.
11.1.2.2Optical Particle Counter.
11.1.2.2.1General: Operate the OPC per the manufacturer's instructions allowing a minimum of 20 minutes warm up before making any measurements.
11.1.2.2.2Overload: The OPC will yield inaccurate data if the aerosol concentration it is attempting to measure exceeds its operating limit. To ensure reliable measurements, the maximum aerosol concentration will not exceed 10 percent of the manufacturer's claimed upper concentration limit corresponding to a 10 percent count error. If this value is exceeded, reduce the aerosol concentration until the acceptable conditions are met.
11.1.2.2.3Zero Count: Connect a HEPA capsule to the inlet of the OPC and obtain printouts for three samples (each a minimum of 1-minute each). Record maximum cumulative zero count. If the count rate exceeds 50 counts per minute, the OPC requires servicing before continuing.
11.1.2.2.4PSL Check of OPC Calibration: Confirm the calibration of the OPC by sampling a known size PSL aerosol. Aerosolize the PSL using an appropriate nebulizer. Record whether the peak count is observed in the proper channel. If the peak is not seen in the appropriate channel, have the OPC recalibrated.
11.1.2.3Test Conditions:
11.1.2.3.1Airflow: The test airflow corresponds to a nominal face velocity of 120 FPM through the arrestor. For arrestors having nominal 20 in.×20 in. face dimensions, this measurement corresponds to an airflow of 333 cfm. For arrestors having nominal face dimensions of 24 in.×24 in., this measurement corresponds to an airflow of 480 cfm.
11.1.2.3.2Temperature and Relative Humidity: The temperature and relative humidity of the challenge air stream will be measured to within an accuracy of ±2 °F and ±10 percent RH. To protect the probe from fouling, it may be removed during periods of aerosol generation.
11.1.2.3.3Barometric Pressure: Use a mercury barometer. Record the atmospheric pressure.
11.1.2.4Upstream and Downstream Background Counts.
11.1.2.4.1With the arrestor installed in the test duct and the airflow set at the proper value, turn on the data acquisition computer and bring up the data acquisition program.
11.1.2.4.2Set the OPC settings for the appropriate test sample duration with output for both printer and computer data collection.
11.1.2.4.3Obtain one set of upstream-downstream background measurements.
11.1.2.4.4After obtaining the upstream-downstream measurements, stop data acquisition.
11.1.2.5Efficiency Measurements:
11.1.2.5.1Record the arrestor pressure drop.
11.1.2.5.2Turn on the Aerosol Generator. Begin aerosol generation and record the operating parameters.
11.1.2.5.3Monitor the particle counts. Allow a minimum of 5 minutes for the generator to stabilize.
11.1.2.5.4Confirm that the total particle count does not exceed the predetermined upper limit. Adjust generator as needed.
11.1.2.5.5Confirm that a minimum of 50 particle counts are measured in the upstream sample in each of the OPC channels per sample. (A minimum of 50 counts per channel per sample will yield the required minimum 500 counts per channel total for the 10 upstream samples as specified in Table 319-1.) Adjust generator or sample time as needed.
11.1.2.5.6If you are unable to obtain a stable concentration within the concentration limit and with the 50 count minimum per channel, adjust the aerosol generator.
11.1.2.5.7When the counts are stable, perform repeated upstream-downstream sampling until 10 upstream-downstream measurements are obtained.
11.1.2.5.8After collection of the 10 upstream-downstream samples, stop data acquisition and allow 2 more minutes for final purging of generator.
11.1.2.5.9Obtain one additional set of upstream-downstream background samples.
11.1.2.5.10After obtaining the upstream-downstream background samples, stop data acquisition.
11.1.2.5.11Record the arrestor pressure drop.
11.1.2.5.12Turn off blower.
11.1.2.5.13Remove the paint arrestor assembly from the test duct. Note any signs of physical deterioration.
11.1.2.5.14Remove the arrestor from the frame and place the arrestor in an appropriate storage bag.
11.2Control Test: 100 Percent Penetration Test. A 100 percent penetration test must be performed immediately before each individual paint arrestor test using the same challenge aerosol substance (i.e., oleic acid or KCl) as to be used in the arrestor test. These tests are performed with no arrestor installed in the test housing. This test is a relatively stringent test of the adequacy of the overall duct, sampling, measurement, and aerosol generation system. The test is performed as a normal penetration test except the paint arrestor is not used. A perfect system would yield a measured penetration of 1 at all particle sizes. Deviations from 1 can occur due to particle losses in the duct, differences in the degree of aerosol uniformity (i.e., mixing) at the upstream and downstream probes, and differences in particle transport efficiency in the upstream and downstream sampling lines.
11.3Control Test: 0 Percent Penetration. One 0 percent penetration test must be performed at least monthly during testing. The test is performed by using a HEPA filter rather than a paint arrestor. This test assesses the adequacy of the instrument response time and sample line lag.
12.0Data Analysis and Calculations
12.1Analysis. The analytical procedures for the fractional penetration and flow velocity measurements are described in Section 11. Note that the primary measurements, those of the upstream and downstream aerosol concentrations, are performed with the OPC which acquires the sample and analyzes it in real time. Because all the test data are collected in real time, there are no analytical procedures performed subsequent to the actual test, only data analysis.
12.2Calculations.
12.2.1Penetration.
Nomenclature
U = Upstream particle count
D = Downstream particle count
Ub = Upstream background count
Db = Downstream background count
P100 = 100 percent penetration value determined immediately prior to the arrestor test computed for each channel as:
P = Penetration of the arrestor corrected for P100
ρ= sample standard deviation
CV = coefficient of variation = ρ/mean
E = Efficiency.
Overbar denotes arithmetic mean of quantity.
Analysis of each test involves the following quantities:
• P100 value for each sizing channel from the 100 percent penetration control test,
• 2 upstream background values,
• 2 downstream background values,
• 10 upstream values with aerosol generator on, and
• 10 downstream values with aerosol generator on.
Using the values associated with each sizing channel, the penetration associated with each particle-sizing channel is calculated as:
Most often, the background levels are small compared to the values when the aerosol generator is on.
12.3The relationship between the physical diameter (DPhysical) as measured by the OPC to the aerodynamic diameter (DAero) is given by:
Where:
pO = unit density of 1 g/cm3.
pParticle = the density of the particle, 0.89 g/cm3 for oleic acid.
CCFPhysical = the Cunningham Correction Factor at DPhysical.
CCFAero = the Cunningham Correction Factor at DAero.
12.4Presentation of Results. For a given arrestor, results will be presented for:
• Triplicate arrestor tests with the liquid-phase challenge aerosol,
sbull; Triplicate arrestor tests with the solid-phase challenge aerosol,
sbull; Triplicate 100 percent penetration tests with the liquid-phase challenge aerosol,
sbull; Triplicate 100 percent penetration tests with the solid-phase challenge aerosol, and
sbull; One 0 percent filter test (using either the liquid-phase or solid-phase aerosol and performed at least monthly).
12.4.1Results for the paint arrestor test must be presented in both graphical and tabular form. The X-axis of the graph will be a logarithmic scale of aerodynamic diameter from 0.1 to 100 µm. The Y-axis will be efficiency (%) on a linear scale from 0 to 100. Plots for each individual run and a plot of the average of triplicate solid-phase and of the average triplicate liquid-phase tests must be prepared. All plots are to be based on point-to-point plotting (i.e., no curve fitting is to be used). The data are to be plotted based on the geometric mean diameter of each of the OPC's sizing channels.
12.4.2Tabulated data from each test must be provided. The data must include the upper and lower diameter bound and geometric mean diameter of each of the OPC sizing channels, the background particle counts for each channel for each sample, the upstream particle counts for each channel for each sample, the downstream particle counts for each channel for each sample, the 100 percent penetration values computed for each channel, and the 0 percent penetration values computed for each channel.
13.0Pollution Prevention
13.1The quantities of materials to be aerosolized should be prepared in accord with the amount needed for the current tests so as to prevent wasteful excess.
14.0Waste Management
14.1Paint arrestors may be returned to originator, if requested, or disposed of with regular laboratory waste.
15.0References
1. Hanley, J.T., D.D. Smith and L. Cox. “Fractional Penetration of Paint Overspray Arrestors, Draft Final Report,” EPA Cooperative Agreement CR-817083-01-0, January 1994.
2. Hanley, J.T., D.D. Smith, and D.S. Ensor. “Define a Fractional Efficiency Test Method that is Compatible with Particulate Removal Air Cleaners Used in General Ventilation,” Final Report, 671-RP, American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc., December 1993.
3. “Project Work and Quality Assurance Plan: Fractional Penetration of Paint Overspray Arrestors, Category II,” EPA Cooperative Agreement No. CR-817083, July 1994.
Test Method 320—Measurement of Vapor Phase Organic and Inorganic Emissions by Extractive Fourier Transform Infrared (FTIR) Spectroscopy
1.0Introduction
Persons unfamiliar with basic elements of FTIR spectroscopy should not attempt to use this method. This method describes sampling and analytical procedures for extractive emission measurements using Fourier transform infrared (FTIR) spectroscopy. Detailed analytical procedures for interpreting infrared spectra are described in the “Protocol for the Use of Extractive Fourier Transform Infrared (FTIR) Spectrometry in Analyses of Gaseous Emissions from Stationary Sources,” hereafter referred to as the “Protocol.” Definitions not given in this method are given in appendix A of the Protocol. References to specific sections in the Protocol are made throughout this Method. For additional information refer to references 1 and 2, and other EPA reports, which describe the use of FTIR spectrometry in specific field measurement applications and validation tests. The sampling procedure described here is extractive. Flue gas is extracted through a heated gas transport and handling system. For some sources, sample conditioning systems may be applicable. Some examples are given in this method.
Note:
sample conditioning systems may be used providing the method validation requirements in Sections 9.2 and 13.0 of this method are met.
1.1Scope and Applicability.
1.1.1Analytes. Analytes include hazardous air pollutants (HAPs) for which EPA reference spectra have been developed. Other compounds can also be measured with this method if reference spectra are prepared according to section 4.6 of the protocol.
1.1.2Applicability. This method applies to the analysis of vapor phase organic or inorganic compounds which absorb energy in the mid-infrared spectral region, about 400 to 4000 cm−1 (25 to 2.5 µm). This method is used to determine compound-specific concentrations in a multi-component vapor phase sample, which is contained in a closed-path gas cell. Spectra of samples are collected using double beam infrared absorption spectroscopy. A computer program is used to analyze spectra and report compound concentrations.
1.2Method Range and Sensitivity. Analytical range and sensitivity depend on the frequency-dependent analyte absorptivity, instrument configuration, data collection parameters, and gas stream composition. Instrument factors include: (a) spectral resolution, (b) interferometer signal averaging time, (c) detector sensitivity and response, and (d) absorption path length.
1.2.1For any optical configuration the analytical range is between the absorbance values of about .01 (infrared transmittance relative to the background = 0.98) and 1.0
(T = 0.1). (For absorbance > 1.0 the relation between absorbance and concentration may not be linear.)
1.2.2The concentrations associated with this absorbance range depend primarily on the cell path length and the sample temperature. An analyte absorbance greater than 1.0, can be lowered by decreasing the optical path length. Analyte absorbance increases with a longer path length. Analyte detection also depends on the presence of other species exhibiting absorbance in the same analytical region. Additionally, the estimated lower absorbance (A) limit
(A = 0.01) depends on the root mean square deviation (RMSD) noise in the analytical region.
1.2.3The concentration range of this method is determined by the choice of optical configuration.
1.2.3.1The absorbance for a given concentration can be decreased by decreasing the path length or by diluting the sample. There is no practical upper limit to the measurement range.
1.2.3.2The analyte absorbance for a given concentration may be increased by increasing the cell path length or (to some extent) using a higher resolution. Both modifications also cause a corresponding increased absorbance for all compounds in the sample, and a decrease in the signal throughput. For this reason the practical lower detection range (quantitation limit) usually depends on sample characteristics such as moisture content of the gas, the presence of other interferants, and losses in the sampling system.
1.3Sensitivity. The limit of sensitivity for an optical configuration and integration time is determined using appendix D of the Protocol: Minimum Analyte Uncertainty, (MAU). The MAU depends on the RMSD noise in an analytical region, and on the absorptivity of the analyte in the same region.
1.4Data Quality. Data quality shall be determined by executing Protocol pre-test procedures in appendices B to H of the protocol and post-test procedures in appendices I and J of the protocol.
1.4.1Measurement objectives shall be established by the choice of detection limit (DLi) and analytical uncertainty (AUi) for each analyte.
1.4.2An instrumental configuration shall be selected. An estimate of gas composition shall be made based on previous test data, data from a similar source or information gathered in a pre-test site survey. Spectral interferants shall be identified using the selected DLi and AUi and band areas from reference spectra and interferant spectra. The baseline noise of the system shall be measured in each analytical region to determine the MAU of the instrument configuration for each analyte and interferant (MIUi).
1.4.3Data quality for the application shall be determined, in part, by measuring the RMS (root mean square) noise level in each analytical spectral region (appendix C of the Protocol). The RMS noise is defined as the RMSD of the absorbance values in an analytical region from the mean absorbance value in the region.
1.4.4The MAU is the minimum analyte concentration for which the AUi can be maintained; if the measured analyte concentration is less than MAUi then data quality are unacceptable.
2.0Summary of Method
2.1Principle. References 4 through 7 provide background material on infrared spectroscopy and quantitative analysis. A summary is given in this section.
2.1.1Infrared absorption spectroscopy is performed by directing an infrared beam through a sample to a detector. The frequency-dependent infrared absorbance of the sample is measured by comparing this detector signal (single beam spectrum) to a signal obtained without a sample in the beam path (background).
2.1.2Most molecules absorb infrared radiation and the absorbance occurs in a characteristic and reproducible pattern. The infrared spectrum measures fundamental molecular properties and a compound can be identified from its infrared spectrum alone.
2.1.3Within constraints, there is a linear relationship between infrared absorption and compound concentration. If this frequency dependent relationship (absorptivity) is known (measured), it can be used to determine compound concentration in a sample mixture.
2.1.4Absorptivity is measured by preparing, in the laboratory, standard samples of compounds at known concentrations and measuring the FTIR “reference spectra” of these standard samples. These “reference spectra” are then used in sample analysis: (1) Compounds are detected by matching sample absorbance bands with bands in reference spectra, and (2) concentrations are measured by comparing sample band intensities with reference band intensities.
2.1.5This method is self-validating provided that the results meet the performance requirement of the QA spike in sections 8.6.2 and 9.0 of this method, and results from a previous method validation study support the use of this method in the application.
2.2Sampling and Analysis. In extractive sampling a probe assembly and pump are used to extract gas from the exhaust of the affected source and transport the sample to the FTIR gas cell. Typically, the sampling apparatus is similar to that used for single-component continuous emission monitor (CEM) measurements.
2.2.1The digitized infrared spectrum of the sample in the FTIR gas cell is measured and stored on a computer. Absorbance band intensities in the spectrum are related to sample concentrations by what is commonly referred to as Beer's Law.
Where:
Ai = absorbance at a given frequency of the ith sample component.
ai = absorption coefficient (absorptivity) of the ith sample component.
b = path length of the cell.
ci = concentration of the ith sample component.
2.2.2Analyte spiking is used for quality assurance (QA). In this procedure (section 8.6.2 of this method) an analyte is spiked into the gas stream at the back end of the sample probe. Analyte concentrations in the spiked samples are compared to analyte concentrations in unspiked samples. Since the concentration of the spike is known, this procedure can be used to determine if the sampling system is removing the spiked analyte(s) from the sample stream.
2.3Reference Spectra Availability. Reference spectra of over 100 HAPs are available in the EPA FTIR spectral library on the EMTIC (Emission Measurement Technical Information Center) computer bulletin board service and at internet address http://info.arnold.af.mil/epa/welcome.htm. Reference spectra for HAPs, or other analytes, may also be prepared according to section 4.6 of the Protocol.
2.4Operator Requirements. The FTIR analyst shall be trained in setting up the instrumentation, verifying the instrument is functioning properly, and performing routine maintenance. The analyst must evaluate the initial sample spectra to determine if the sample matrix is consistent with pre-test assumptions and if the instrument configuration is suitable. The analyst must be able to modify the instrument configuration, if necessary.
2.4.1The spectral analysis shall be supervised by someone familiar with EPA FTIR Protocol procedures.
2.4.2A technician trained in instrumental test methods is qualified to install and operate the sampling system. This includes installing the probe and heated line assembly, operating the analyte spike system, and performing moisture and flow measurements.
3.0Definitions
See appendix A of the Protocol for definitions relating to infrared spectroscopy. Additional definitions are given in sections 3.1 through 3.29.
3.1Analyte. A compound that this method is used to measure. The term “target analyte” is also used. This method is multi-component and a number of analytes can be targeted for a test.
3.2Reference Spectrum. Infrared spectrum of an analyte prepared under controlled, documented, and reproducible laboratory conditions according to procedures in section 4.6 of the Protocol. A library of reference spectra is used to measure analytes in gas samples.
3.3Standard Spectrum. A spectrum that has been prepared from a reference spectrum through a (documented) mathematical operation. A common example is de-resolving of reference spectra to lower-resolution standard spectra (Protocol, appendix K to the addendum of this method). Standard spectra, prepared by approved, and documented, procedures can be used as reference spectra for analysis.
3.4Concentration. In this method concentration is expressed as a molar concentration, in ppm-meters, or in (ppm-meters)/K, where K is the absolute temperature (Kelvin). The latter units allow the direct comparison of concentrations from systems using different optical configurations or sampling temperatures.
3.5Interferant. A compound in the sample matrix whose infrared spectrum overlaps with part of an analyte spectrum. The most accurate analyte measurements are achieved when reference spectra of interferants are used in the quantitative analysis with the analyte reference spectra. The presence of an interferant can increase the analytical uncertainty in the measured analyte concentration.
3.6Gas Cell. A gas containment cell that can be evacuated. It is equipped with the optical components to pass the infrared beam through the sample to the detector. Important cell features include: path length (or range if variable), temperature range, materials of construction, and total gas volume.
3.7Sampling System. Equipment used to extract the sample from the test location and transport the sample gas to the FTIR analyzer. This includes sample conditioning systems.
3.8Sample Analysis. The process of interpreting the infrared spectra to obtain sample analyte concentrations. This process is usually automated using a software routine employing a classical least squares (cls), partial least squares (pls), or K- or P-matrix method.
3.9One hundred percent line. A double beam transmittance spectrum obtained by combining two background single beam spectra. Ideally, this line is equal to 100 percent transmittance (or zero absorbance) at every frequency in the spectrum. Practically, a zero absorbance line is used to measure the baseline noise in the spectrum.
3.10Background Deviation. A deviation from 100 percent transmittance in any region of the 100 percent line. Deviations greater than ±5 percent in an analytical region are unacceptable (absorbance of 0.021 to −0.022). Such deviations indicate a change in the instrument throughput relative to the background single beam.
3.11Batch Sampling. A procedure where spectra of discreet, static samples are collected. The gas cell is filled with sample and the cell is isolated. The spectrum is collected. Finally, the cell is evacuated to prepare for the next sample.
3.12Continuous Sampling. A procedure where spectra are collected while sample gas is flowing through the cell at a measured rate.
3.13Sampling resolution. The spectral resolution used to collect sample spectra.
3.14Truncation. Limiting the number of interferogram data points by deleting points farthest from the center burst (zero path difference, ZPD).
3.15Zero filling. The addition of points to the interferogram. The position of each added point is interpolated from neighboring real data points. Zero filling adds no information to the interferogram, but affects line shapes in the absorbance spectrum (and possibly analytical results).
3.16Reference CTS. Calibration Transfer Standard spectra that were collected with reference spectra.
3.17CTS Standard. CTS spectrum produced by applying a de-resolution procedure to a reference CTS.
3.18Test CTS. CTS spectra collected at the sampling resolution using the same optical configuration as for sample spectra. Test spectra help verify the resolution, temperature and path length of the FTIR system.
3.19RMSD. Root Mean Square Difference, defined in EPA FTIR Protocol, appendix A.
3.20Sensitivity. The noise-limited compound-dependent detection limit for the FTIR system configuration. This is estimated by the MAU. It depends on the RMSD in an analytical region of a zero absorbance line.
3.21Quantitation Limit. The lower limit of detection for the FTIR system configuration in the sample spectra. This is estimated by mathematically subtracting scaled reference spectra of analytes and interferences from sample spectra, then measuring the RMSD in an analytical region of the subtracted spectrum. Since the noise in subtracted sample spectra may be much greater than in a zero absorbance spectrum, the quantitation limit is generally much higher than the sensitivity. Removing spectral interferences from the sample or improving the spectral subtraction can lower the quantitation limit toward (but not below) the sensitivity.
3.22Independent Sample. A unique volume of sample gas; there is no mixing of gas between two consecutive independent samples. In continuous sampling two independent samples are separated by at least 5 cell volumes. The interval between independent measurements depends on the cell volume and the sample flow rate (through the cell).
3.23Measurement. A single spectrum of flue gas contained in the FTIR cell.
3.24Run. A run consists of a series of measurements. At a minimum a run includes 8 independent measurements spaced over 1 hour.
3.25Validation. Validation of FTIR measurements is described in sections 13.0 through 13.4 of this method. Validation is used to verify the test procedures for measuring specific analytes at a source. Validation provides proof that the method works under certain test conditions.
3.26Validation Run. A validation run consists of at least 24 measurements of independent samples. Half of the samples are spiked and half are not spiked. The length of the run is determined by the interval between independent samples.
3.27ning. Screening is used when there is little or no available information about a source. The purpose of screening is to determine what analytes are emitted and to obtain information about important sample characteristics such as moisture, temperature, and interferences. Screening results are semi-quantitative (estimated concentrations) or qualitative (identification only). Various optical and sampling configurations may be used. Sample conditioning systems may be evaluated for their effectiveness in removing interferences. It is unnecessary to perform a complete run under any set of sampling conditions. Spiking is not necessary, but spiking can be a useful screening tool for evaluating the sampling system, especially if a reactive or soluble analyte is used for the spike.
3.28Emissions Test. An FTIR emissions test is performed according specific sampling and analytical procedures. These procedures, for the target analytes and the source, are based on previous screening and validation results. Emission results are quantitative. A QA spike (sections 8.6.2 and 9.2 of this method) is performed under each set of sampling conditions using a representative analyte. Flow, gas temperature and diluent data are recorded concurrently with the FTIR measurements to provide mass emission rates for detected compounds.
3.29Surrogate. A surrogate is a compound that is used in a QA spike procedure (section 8.6.2 of this method) to represent other compounds. The chemical and physical properties of a surrogate shall be similar to the compounds it is chosen to represent. Under given sampling conditions, usually a single sampling factor is of primary concern for measuring the target analytes: for example, the surrogate spike results can be representative for analytes that are more reactive, more soluble, have a lower absorptivity, or have a lower vapor pressure than the surrogate itself.
4.0Interferences
Interferences are divided into two classifications: analytical and sampling.
4.1Analytical Interferences. An analytical interference is a spectral feature that complicates (in extreme cases may prevent) the analysis of an analyte. Analytical interferences are classified as background or spectral interference.
4.1.1Background Interference. This results from a change in throughput relative to the single beam background. It is corrected by collecting a new background and proceeding with the test. In severe instances the cause must be identified and corrected. Potential causes include: (1) Deposits on reflective surfaces or transmitting windows, (2) changes in detector sensitivity, (3) a change in the infrared source output, or (4) failure in the instrument electronics. In routine sampling throughput may degrade over several hours. Periodically a new background must be collected, but no other corrective action will be required.
4.1.2Spectral Interference. This results from the presence of interfering compound(s) (interferant) in the sample. Interferant spectral features overlap analyte spectral features. Any compound with an infrared spectrum, including analytes, can potentially be an interferant. The Protocol measures absorbance band overlap in each analytical region to determine if potential interferants shall be classified as known interferants (FTIR Protocol, section 4.9 and appendix B). Water vapor and CO2 are common spectral interferants. Both of these compounds have strong infrared spectra and are present in many sample matrices at high concentrations relative to analytes. The extent of interference depends on the (1) interferant concentration, (2) analyte concentration, and (3) the degree of band overlap. Choosing an alternate analytical region can minimize or avoid the spectral interference. For example, CO2 interferes with the analysis of the 670 cm−1 benzene band. However, benzene can also be measured near 3000 cm−1 (with less sensitivity).
4.2Sampling System Interferences. These prevent analytes from reaching the instrument. The analyte spike procedure is designed to measure sampling system interference, if any.
4.2.1Temperature. A temperature that is too low causes condensation of analytes or water vapor. The materials of the sampling system and the FTIR gas cell usually set the upper limit of temperature.
4.2.2Reactive Species. Anything that reacts with analytes. Some analytes, like formaldehyde, polymerize at lower temperatures.
4.2.3Materials. Poor choice of material for probe, or sampling line may remove some analytes. For example, HF reacts with glass components.
4.2.4Moisture. In addition to being a spectral interferant, condensed moisture removes soluble compounds.
5.0Safety
The hazards of performing this method are those associated with any stack sampling method and the same precautions shall be followed. Many HAPs are suspected carcinogens or present other serious health risks. Exposure to these compounds should be avoided in all circumstances. For instructions on the safe handling of any particular compound, refer to its material safety data sheet. When using analyte standards, always ensure that gases are properly vented and that the gas handling system is leak free. (Always perform a leak check with the system under maximum vacuum and, again, with the system at greater than ambient pressure.) Refer to section 8.2 of this method for leak check procedures. This method does not address all of the potential safety risks associated with its use. Anyone performing this method must follow safety and health practices consistent with applicable legal requirements and with prudent practice for each application.
6.0Equipment and Supplies
Note:
Mention of trade names or specific products does not constitute endorsement by the Environmental Protection Agency.
The equipment and supplies are based on the schematic of a sampling system shown in Figure 1. Either the batch or continuous sampling procedures may be used with this sampling system. Alternative sampling configurations may also be used, provided that the data quality objectives are met as determined in the post-analysis evaluation. Other equipment or supplies may be necessary, depending on the design of the sampling system or the specific target analytes.
6.1Sampling Probe. Glass, stainless steel, or other appropriate material of sufficient length and physical integrity to sustain heating, prevent adsorption of analytes, and to transport analytes to the infrared gas cell. Special materials or configurations may be required in some applications. For instance, high stack sample temperatures may require special steel or cooling the probe. For very high moisture sources it may be desirable to use a dilution probe.
6.2Particulate Filters. A glass wool plug (optional) inserted at the probe tip (for large particulate removal) and a filter (required) rated for 99 percent removal efficiency at 1-micron (e.g., Balston”) connected at the outlet of the heated probe.
6.3Sampling Line/Heating System. Heated (sufficient to prevent condensation) stainless steel, polytetrafluoroethane, or other material inert to the analytes.
6.4Gas Distribution Manifold. A heated manifold allowing the operator to control flows of gas standards and samples directly to the FTIR system or through sample conditioning systems. Usually includes heated flow meter, heated valve for selecting and sending sample to the analyzer, and a by-pass vent. This is typically constructed of stainless steel tubing and fittings, and high-temperature valves.
6.5Stainless Steel Tubing. Type 316, appropriate diameter (e.g., 3/8 in.) and length for heated connections. Higher grade stainless may be desirable in some applications.
6.6Calibration/Analyte Spike Assembly. A three way valve assembly (or equivalent) to introduce analyte or surrogate spikes into the sampling system at the outlet of the probe upstream of the out-of-stack particulate filter and the FTIR analytical system.
6.7Mass Flow Meter (MFM). These are used for measuring analyte spike flow. The MFM shall be calibrated in the range of 0 to 5 L/min and be accurate to ±2 percent (or better) of the flow meter span.
6.8Gas Regulators. Appropriate for individual gas standards.
6.9Polytetrafluoroethane Tubing. Diameter (e.g., 3/8 in.) and length suitable to connect cylinder regulators to gas standard manifold.
6.10Sample Pump. A leak-free pump (e.g., KNF TM), with by-pass valve, capable of producing a sample flow rate of at least 10 L/min through 100 ft of sample line. If the pump is positioned upstream of the distribution manifold and FTIR system, use a heated pump that is constructed from materials non-reactive to the analytes. If the pump is located downstream of the FTIR system, the gas cell sample pressure will be lower than ambient pressure and it must be recorded at regular intervals.
6.11Gas Sample Manifold. Secondary manifold to control sample flow at the inlet to the FTIR manifold. This is optional, but includes a by-pass vent and heated rotameter.
6.12Rotameter. A 0 to 20 L/min rotameter. This meter need not be calibrated.
6.13FTIR Analytical System. Spectrometer and detector, capable of measuring the analytes to the chosen detection limit. The system shall include a personal computer with compatible software allowing automated collection of spectra.
6.14FTIR Cell Pump. Required for the batch sampling technique, capable of evacuating the FTIR cell volume within 2 minutes. The pumping speed shall allow the operator to obtain 8 sample spectra in 1 hour.
6.15Absolute Pressure Gauge. Capable of measuring pressure from 0 to 1000 mmHg to within ±2.5 mmHg (e.g., Baratron TM).
6.16Temperature Gauge. Capable of measuring the cell temperature to within ±2 °C.
6.17Sample Conditioning. One option is a condenser system, which is used for moisture removal. This can be helpful in the measurement of some analytes. Other sample conditioning procedures may be devised for the removal of moisture or other interfering species.
6.17.1The analyte spike procedure of section 9.2 of this method, the QA spike procedure of section 8.6.2 of this method, and the validation procedure of section 13 of this method demonstrate whether the sample conditioning affects analyte concentrations. Alternatively, measurements can be made with two parallel FTIR systems; one measuring conditioned sample, the other measuring unconditioned sample.
6.17.2Another option is sample dilution. The dilution factor measurement must be documented and accounted for in the reported concentrations. An alternative to dilution is to lower the sensitivity of the FTIR system by decreasing the cell path length, or to use a short-path cell in conjunction with a long path cell to measure more than one concentration range.
7.0Reagents and Standards
7.1Analyte(s) and Tracer Gas. Obtain a certified gas cylinder mixture containing all of the analyte(s) at concentrations within ±2 percent of the emission source levels (expressed in ppm-meter/K). If practical, the analyte standard cylinder shall also contain the tracer gas at a concentration which gives a measurable absorbance at a dilution factor of at least 10:1. Two ppm SF6 is sufficient for a path length of 22 meters at 250 °F.
7.2Calibration Transfer Standard(s). Select the calibration transfer standards (CTS) according to section 4.5 of the FTIR Protocol. Obtain a National Institute of Standards and Technology (NIST) traceable gravimetric standard of the CTS (±2 percent).
7.3Reference Spectra. Obtain reference spectra for each analyte, interferant, surrogate, CTS, and tracer. If EPA reference spectra are not available, use reference spectra prepared according to procedures in section 4.6 of the EPA FTIR Protocol.
8.0Sampling and Analysis Procedure
Three types of testing can be performed: (1) Screening, (2) emissions test, and (3) validation. Each is defined in section 3 of this method. Determine the purpose(s) of the FTIR test. Test requirements include: (a) AUi, DLi, overall fractional uncertainty, OFUi, maximum expected concentration (CMAXi), and tAN for each, (b) potential interferants, (c) sampling system factors, e.g., minimum absolute cell pressure, (Pmin), FTIR cell volume (VSS), estimated sample absorption pathlength, LS′, estimated sample pressure, PS′, TS′, signal integration time (tSS), minimum instrumental linewidth, MIL, fractional error, and (d) analytical regions, e.g., m = 1 to M, lower wavenumber position, FLm, center wavenumber position, FCm, and upper wavenumber position, FUm, plus interferants, upper wavenumber position of the CTS absorption band, FFUm, lower wavenumber position of the CTS absorption band, FFLm, wavenumber range FNU to FNL. If necessary, sample and acquire an initial spectrum. From analysis of this preliminary spectrum determine a suitable operational path length. Set up the sampling train as shown in Figure 1 or use an appropriate alternative configuration. Sections 8.1 through 8.11 of this method provide guidance on pre-test calculations in the EPA protocol, sampling and analytical procedures, and post-test protocol calculations.
8.1Pretest Preparations and Evaluations. Using the procedure in section 4.0 of the FTIR Protocol, determine the optimum sampling system configuration for measuring the target analytes. Use available information to make reasonable assumptions about moisture content and other interferences.
8.1.1Analytes. Select the required detection limit (DLi) and the maximum permissible analytical uncertainty (AUi) for each analyte (labeled from 1 to i). Estimate, if possible, the maximum expected concentration for each analyte, CMAXi. The expected measurement range is fixed by DLi and CMAXi for each analyte (i).
8.1.2Potential Interferants. List the potential interferants. This usually includes water vapor and CO2, but may also include some analytes and other compounds.
8.1.3.Optical Configuration. Choose an optical configuration that can measure all of the analytes within the absorbance range of .01 to 1.0 (this may require more than one path length). Use Protocol sections 4.3 to 4.8 for guidance in choosing a configuration and measuring CTS.
8.1.4Fractional Reproducibility Uncertainty (FRU i). The FRU is determined for each analyte by comparing CTS spectra taken before and after the reference spectra were measured. The EPA para-xylene reference spectra were collected on 10/31/91 and 11/01/91 with corresponding CTS spectra “cts1031a,” and “cts1101b.” The CTS spectra are used to estimate the reproducibility (FRU) in the system that was used to collect the references. The FRU must be < AU. Appendix E of the protocol is used to calculate the FRU from CTS spectra. Figure 2 plots results for 0.25 cm−1 CTS spectra in EPA reference library: S3 (cts1101b−cts1031a), and S4 [(cts1101b cts1031a)/2]. The RMSD (SRMS) is calculated in the subtracted baseline, S3, in the corresponding CTS region from 850 to 1065 cm−1. The area (BAV) is calculated in the same region of the averaged CTS spectrum, S4.
8.1.5Known Interferants. Use appendix B of the EPA FTIR Protocol.
8.1.6Calculate the Minimum Analyte Uncertainty, MAU (section 1.3 of this method discusses MAU and protocol appendix D gives the MAU procedure). The MAU for each analyte, i, and each analytical region, m, depends on the RMS noise.
8.1.7Analytical Program. See FTIR Protocol, section 4.10. Prepare computer program based on the chosen analytical technique. Use as input reference spectra of all target analytes and expected interferants. Reference spectra of additional compounds shall also be included in the program if their presence (even if transient) in the samples is considered possible. The program output shall be in ppm (or ppb) and shall be corrected for differences between the reference path length, LR, temperature, TR, and pressure, PR, and the conditions used for collecting the sample spectra. If sampling is performed at ambient pressure, then any pressure correction is usually small relative to corrections for path length and temperature, and may be neglected.
8.2Leak-Check
8.2.1Sampling System. A typical FTIR extractive sampling train is shown in Figure 1. Leak check from the probe tip to pump outlet as follows: Connect a 0-to 250-mL/min rate meter (rotameter or bubble meter) to the outlet of the pump. Close off the inlet to the probe, and record the leak rate. The leak rate shall be ≤200 mL/min.
8.2.2Analytical System Leak check. Leak check the FTIR cell under vacuum and under pressure (greater than ambient). Leak check connecting tubing and inlet manifold under pressure.
8.2.2.1For the evacuated sample technique, close the valve to the FTIR cell, and evacuate the absorption cell to the minimum absolute pressure Pmin. Close the valve to the pump, and determine the change in pressure ΔPv after 2 minutes.
8.2.2.2For both the evacuated sample and purging techniques, pressurize the system to about 100 mmHg above atmospheric pressure. Isolate the pump and determine the change in pressure ΔPp after 2 minutes.
8.2.2.3Measure the barometric pressure, Pb in mmHg.
8.2.2.4Determine the percent leak volume %VL for the signal integration time tSS and for ΔPmax, i.e., the larger of ΔPv or ΔPp, as follows:
where 50 = 100% divided by the leak-check time of 2 minutes. 8.2.2.5 Leak volumes in excess of 4 percent of the FTIR system volume VSS are unacceptable.
8.3Detector Linearity. Once an optical configuration is chosen, use one of the procedures of sections 8.3.1 through 8.3.3 to verify that the detector response is linear. If the detector response is not linear, decrease the aperture, or attenuate the infrared beam. After a change in the instrument configuration perform a linearity check until it is demonstrated that the detector response is linear.
8.3.1Vary the power incident on the detector by modifying the aperture setting. Measure the background and CTS at three instrument aperture settings: (1) at the aperture setting to be used in the testing, (2) at one half this aperture and (3) at twice the proposed testing aperture. Compare the three CTS spectra. CTS band areas shall agree to within the uncertainty of the cylinder standard and the RMSD noise in the system. If test aperture is the maximum aperture, collect CTS spectrum at maximum aperture, then close the aperture to reduce the IR throughput by half. Collect a second background and CTS at the smaller aperture setting and compare the spectra again.
8.3.2Use neutral density filters to attenuate the infrared beam. Set up the FTIR system as it will be used in the test measurements. Collect a CTS spectrum. Use a neutral density filter to attenuate the infrared beam (either immediately after the source or the interferometer) to approximately 1/2 its original intensity. Collect a second CTS spectrum. Use another filter to attenuate the infrared beam to approximately 1/4 its original intensity. Collect a third background and CTS spectrum. Compare the CTS spectra. CTS band areas shall agree to within the uncertainty of the cylinder standard and the RMSD noise in the system.
8.3.3Observe the single beam instrument response in a frequency region where the detector response is known to be zero. Verify that the detector response is “flat” and equal to zero in these regions.
8.4Data Storage Requirements. All field test spectra shall be stored on a computer disk and a second backup copy must stored on a separate disk. The stored information includes sample interferograms, processed absorbance spectra, background interferograms, CTS sample interferograms and CTS absorbance spectra. Additionally, documentation of all sample conditions, instrument settings, and test records must be recorded on hard copy or on computer medium. Table 1 gives a sample presentation of documentation.
8.5Background Spectrum. Evacuate the gas cell to ≤5 mmHg, and fill with dry nitrogen gas to ambient pressure (or purge the cell with 10 volumes of dry nitrogen). Verify that no significant amounts of absorbing species (for example water vapor and CO2) are present. Collect a background spectrum, using a signal averaging period equal to or greater than the averaging period for the sample spectra. Assign a unique file name to the background spectrum. Store two copies of the background interferogram and processed single-beam spectrum on separate computer disks (one copy is the back-up).
8.5.1Interference Spectra. If possible, collect spectra of known and suspected major interferences using the same optical system that will be used in the field measurements. This can be done on-site or earlier. A number of gases, e.g. CO2, SO2, CO, NH3, are readily available from cylinder gas suppliers.
8.5.2Water vapor spectra can be prepared by the following procedure. Fill a sample tube with distilled water. Evacuate above the sample and remove dissolved gasses by alternately freezing and thawing the water while evacuating. Allow water vapor into the FTIR cell, then dilute to atmospheric pressure with nitrogen or dry air. If quantitative water spectra are required, follow the reference spectrum procedure for neat samples (protocol, section 4.6). Often, interference spectra need not be quantitative, but for best results the absorbance must be comparable to the interference absorbance in the sample spectra.
8.6Pre-Test Calibrations
8.6.1Calibration Transfer Standard. Evacuate the gas cell to ≤ 5 mmHg absolute pressure, and fill the FTIR cell to atmospheric pressure with the CTS gas. Alternatively, purge the cell with 10 cell volumes of CTS gas. (If purge is used, verify that the CTS concentration in the cell is stable by collecting two spectra 2 minutes apart as the CTS gas continues to flow. If the absorbance in the second spectrum is no greater than in the first, within the uncertainty of the gas standard, then this can be used as the CTS spectrum.) Record the spectrum.
8.6.2QA Spike. This procedure assumes that the method has been validated for at least some of the target analytes at the source. For emissions testing perform a QA spike. Use a certified standard, if possible, of an analyte, which has been validated at the source. One analyte standard can serve as a QA surrogate for other analytes which are less reactive or less soluble than the standard. Perform the spike procedure of section 9.2 of this method. Record spectra of at least three independent (section 3.22 of this method) spiked samples. Calculate the spiked component of the analyte concentration. If the average spiked concentration is within 0.7 to 1.3 times the expected concentration, then proceed with the testing. If applicable, apply the correction factor from the Method 301 of this appendix validation test (not the result from the QA spike).
8.7Sampling. If analyte concentrations vary rapidly with time, continuous sampling is preferable using the smallest cell volume, fastest sampling rate and fastest spectra collection rate possible. Continuous sampling requires the least operator intervention even without an automated sampling system. For continuous monitoring at one location over long periods, Continuous sampling is preferred. Batch sampling and continuous static sampling are used for screening and performing test runs of finite duration. Either technique is preferred for sampling several locations in a matter of days. Batch sampling gives reasonably good time resolution and ensures that each spectrum measures a discreet (and unique) sample volume. Continuous static (and continuous) sampling provide a very stable background over long periods. Like batch sampling, continuous static sampling also ensures that each spectrum measures a unique sample volume. It is essential that the leak check procedure under vacuum (section 8.2 of this method) is passed if the batch sampling procedure is used. It is essential that the leak check procedure under positive pressure is passed if the continuous static or continuous sampling procedures are used. The sampling techniques are described in sections 8.7.1 through 8.7.2 of this method.
8.7.1Batch Sampling. Evacuate the absorbance cell to ≤5 mmHg absolute pressure. Fill the cell with exhaust gas to ambient pressure, isolate the cell, and record the spectrum. Before taking the next sample, evacuate the cell until no spectral evidence of sample absorption remains. Repeat this procedure to collect eight spectra of separate samples in 1 hour.
8.7.2Continuous Static Sampling. Purge the FTIR cell with 10 cell volumes of sample gas. Isolate the cell, collect the spectrum of the static sample and record the pressure. Before measuring the next sample, purge the cell with 10 more cell volumes of sample gas.
8.8Sampling QA and Reporting
8.8.1Sample integration times shall be sufficient to achieve the required signal-to-noise ratio. Obtain an absorbance spectrum by filling the cell with N2. Measure the RMSD in each analytical region in this absorbance spectrum. Verify that the number of scans used is sufficient to achieve the target MAU.
8.8.2Assign a unique file name to each spectrum.
8.8.3Store two copies of sample interferograms and processed spectra on separate computer disks.
8.8.4For each sample spectrum, document the sampling conditions, the sampling time (while the cell was being filled), the time the spectrum was recorded, the instrumental conditions (path length, temperature, pressure, resolution, signal integration time), and the spectral file name. Keep a hard copy of these data sheets.
8.9Signal Transmittance. While sampling, monitor the signal transmittance. If signal transmittance (relative to the background) changes by 5 percent or more (absorbance = -.02 to .02) in any analytical spectral region, obtain a new background spectrum.
8.10Post-test CTS. After the sampling run, record another CTS spectrum.
8.11Post-test QA
8.11.1Inspect the sample spectra immediately after the run to verify that the gas matrix composition was close to the expected (assumed) gas matrix.
8.11.2Verify that the sampling and instrumental parameters were appropriate for the conditions encountered. For example, if the moisture is much greater than anticipated, it may be necessary to use a shorter path length or dilute the sample.
8.11.3Compare the pre- and post-test CTS spectra. The peak absorbance in pre- and post-test CTS must be ±5 percent of the mean value. See appendix E of the FTIR Protocol.
9.0Quality Control
Use analyte spiking (sections 8.6.2, 9.2 and 13.0 of this method) to verify that the sampling system can transport the analytes from the probe to the FTIR system.
9.1Spike Materials. Use a certified standard (accurate to ±2 percent) of the target analyte, if one can be obtained. If a certified standard cannot be obtained, follow the procedures in section 4.6.2.2 of the FTIR Protocol.
9.2Spiking Procedure. QA spiking (section 8.6.2 of this method) is a calibration procedure used before testing. QA spiking involves following the spike procedure of sections 9.2.1 through 9.2.3 of this method to obtain at least three spiked samples. The analyte concentrations in the spiked samples shall be compared to the expected spike concentration to verify that the sampling/analytical system is working properly. Usually, when QA spiking is used, the method has already been validated at a similar source for the analyte in question. The QA spike demonstrates that the validated sampling/analytical conditions are being duplicated. If the QA spike fails then the sampling/analytical system shall be repaired before testing proceeds. The method validation procedure (section 13.0 of this method) involves a more extensive use of the analyte spike procedure of sections 9.2.1 through 9.2.3 of this method. Spectra of at least 12 independent spiked and 12 independent unspiked samples are recorded. The concentration results are analyzed statistically to determine if there is a systematic bias in the method for measuring a particular analyte. If there is a systematic bias, within the limits allowed by Method 301 of this appendix, then a correction factor shall be applied to the analytical results. If the systematic bias is greater than the allowed limits, this method is not valid and cannot be used.
9.2.1Introduce the spike/tracer gas at a constant flow rate of ≤10 percent of the total sample flow, when possible.
Note:
Use the rotameter at the end of the sampling train to estimate the required spike/tracer gas flow rate.
Use a flow device, e.g., mass flow meter (# 2 percent), to monitor the spike flow rate. Record the spike flow rate every 10 minutes.
9.2.2Determine the response time (RT) of the system by continuously collecting spectra of the spiked effluent until the spectrum of the spiked component is constant for 5 minutes. The RT is the interval from the first measurement until the spike becomes constant. Wait for twice the duration of the RT, then collect spectra of two independent spiked gas samples. Duplicate analyses of the spiked concentration shall be within 5 percent of the mean of the two measurements.
9.2.3Calculate the dilution ratio using the tracer gas as follows: where:
Where:
DF=Dilution factor of the spike gas; this value shall be ≥10.
SF6(dir)=SF6 (or tracer gas) concentration measured directly in undiluted spike gas.
SF6(spk)=Diluted SF6 (or tracer gas) concentration measured in a spiked sample.
Spikedir=Concentration of the analyte in the spike standard measured by filling the FTIR cell directly.
CS=Expected concentration of the spiked samples.
Unspike=Native concentration of analytes in unspiked samples.
10.0Calibration and Standardization
10.1Signal-to-Noise Ratio (S/N). The RMSD in the noise must be less than one tenth of the minimum analyte peak absorbance in each analytical region. For example if the minimum peak absorbance is 0.01 at the required DL, then RMSD measured over the entire analytical region must be ≤0.001.
10.2Absorbance Path length. Verify the absorbance path length by comparing reference CTS spectra to test CTS spectra. See appendix E of the FTIR Protocol.
10.3Instrument Resolution. Measure the line width of appropriate test CTS band(s) to verify instrument resolution. Alternatively, compare CTS spectra to a reference CTS spectrum, if available, measured at the nominal resolution.
10.4Apodization Function.In transforming the sample interferograms to absorbance spectra use the same apodization function that was used in transforming the reference spectra.
10.5FTIR Cell Volume. Evacuate the cell to ≤5 mmHg. Measure the initial absolute temperature (Ti) and absolute pressure (Pi). Connect a wet test meter (or a calibrated dry gas meter), and slowly draw room air into the cell. Measure the meter volume (Vm), meter absolute temperature (Tm), and meter absolute pressure (Pm); and the cell final absolute temperature (Tf) and absolute pressure (Pf). Calculate the FTIR cell volume VSS, including that of the connecting tubing, as follows:
11.0Data Analysis and Calculations
Analyte concentrations shall be measured using reference spectra from the EPA FTIR spectral library. When EPA library spectra are not available, the procedures in section 4.6 of the Protocol shall be followed to prepare reference spectra of all the target analytes.
11.1Spectral De-resolution. Reference spectra can be converted to lower resolution standard spectra (section 3.3 of this method) by truncating the original reference sample and background interferograms. Appendix K of the FTIR Protocol gives specific deresolution procedures. Deresolved spectra shall be transformed using the same apodization function and level of zero filling as the sample spectra. Additionally, pre-test FTIR protocol calculations (e.g., FRU, MAU, FCU) shall be performed using the de-resolved standard spectra.
11.2Data Analysis. Various analytical programs are available for relating sample absorbance to a concentration standard. Calculated concentrations shall be verified by analyzing residual baselines after mathematically subtracting scaled reference spectra from the sample spectra. A full description of the data analysis and calculations is contained in the FTIR Protocol (sections 4.0, 5.0, 6.0 and appendices). Correct the calculated concentrations in the sample spectra for differences in absorption path length and temperature between the reference and sample spectra using equation 6,
Where:
Ccorr=Concentration, corrected for path length.
Ccalc=Concentration, initial calculation (output of the analytical program designed for the compound).
Lr=Reference spectra path length.
Ls=Sample spectra path length.
Ts=Absolute temperature of the sample gas, K.
Tr=Absolute gas temperature of reference spectra, K.
Ps=Sample cell pressure.
Pr=Reference spectrum sample pressure.
12.0Method Performance
12.1Spectral Quality. Refer to the FTIR Protocol appendices for analytical requirements, evaluation of data quality, and analysis of uncertainty.
12.2Sampling QA/QC. The analyte spike procedure of section 9 of this method, the QA spike of section 8.6.2 of this method, and the validation procedure of section 13 of this method are used to evaluate the performance of the sampling system and to quantify sampling system effects, if any, on the measured concentrations. This method is self-validating provided that the results meet the performance requirement of the QA spike in sections 9.0 and 8.6.2 of this method and results from a previous method validation study support the use of this method in the application. Several factors can contribute to uncertainty in the measurement of spiked samples. Factors which can be controlled to provide better accuracy in the spiking procedure are listed in sections 12.2.1 through 12.2.4 of this method.
12.2.1Flow meter. An accurate mass flow meter is accurate to ±1 percent of its span. If a flow of 1 L/min is monitored with such a MFM, which is calibrated in the range of 0-5 L/min, the flow measurement has an uncertainty of 5 percent. This may be improved by re-calibrating the meter at the specific flow rate to be used.
12.2.2Calibration gas. Usually the calibration standard is certified to within ±2 percent. With reactive analytes, such as HCl, the certified accuracy in a commercially available standard may be no better than ±5 percent.
12.2.3Temperature. Temperature measurements of the cell shall be quite accurate. If practical, it is preferable to measure sample temperature directly, by inserting a thermocouple into the cell chamber instead of monitoring the cell outer wall temperature.
12.2.4Pressure. Accuracy depends on the accuracy of the barometer, but fluctuations in pressure throughout a day may be as much as 2.5 percent due to weather variations.
13.0Method Validation Procedure
This validation procedure, which is based on EPA Method 301 (40 CFR part 63, appendix (A), may be used to validate this method for the analytes in a gas matrix. Validation at one source may also apply to another type of source, if it can be shown that the exhaust gas characteristics are similar at both sources.
13.1Section 5.3 of Method 301 (40 CFR part 63, appendix A), the Analyte Spike procedure, is used with these modifications. The statistical analysis of the results follows section 6.3 of EPA Method 301. Section 3 of this method defines terms that are not defined in Method 301.
13.1.1The analyte spike is performed dynamically. This means the spike flow is continuous and constant as spiked samples are measured.
13.1.2The spike gas is introduced at the back of the sample probe.
13.1.3Spiked effluent is carried through all sampling components downstream of the probe.
13.1.4A single FTIR system (or more) may be used to collect and analyze spectra (not quadruplicate integrated sampling trains).
13.1.5All of the validation measurements are performed sequentially in a single “run” (section 3.26 of this method).
13.1.6The measurements analyzed statistically are each independent (section 3.22 of this method).
13.1.7A validation data set can consist of more than 12 spiked and 12 unspiked measurements.
13.2Batch Sampling. The procedure in sections 13.2.1 through 13.2.2 may be used for stable processes. If process emissions are highly variable, the procedure in section 13.2.3 shall be used.
13.2.1With a single FTIR instrument and sampling system, begin by collecting spectra of two unspiked samples. Introduce the spike flow into the sampling system and allow 10 cell volumes to purge the sampling system and FTIR cell. Collect spectra of two spiked samples. Turn off the spike and allow 10 cell volumes of unspiked sample to purge the FTIR cell. Repeat this procedure until the 24 (or more) samples are collected.
13.2.2In batch sampling, collect spectra of 24 distinct samples. (Each distinct sample consists of filling the cell to ambient pressure after the cell has been evacuated.)
13.2.3Alternatively, a separate probe assembly, line, and sample pump can be used for spiked sample. Verify and document that sampling conditions are the same in both the spiked and the unspiked sampling systems. This can be done by wrapping both sample lines in the same heated bundle. Keep the same flow rate in both sample lines. Measure samples in sequence in pairs. After two spiked samples are measured, evacuate the FTIR cell, and turn the manifold valve so that spiked sample flows to the FTIR cell. Allow the connecting line from the manifold to the FTIR cell to purge thoroughly (the time depends on the line length and flow rate). Collect a pair of spiked samples. Repeat the procedure until at least 24 measurements are completed.
13.3Simultaneous Measurements With Two FTIR Systems. If unspiked effluent concentrations of the target analyte(s) vary significantly with time, it may be desirable to perform synchronized measurements of spiked and unspiked sample. Use two FTIR systems, each with its own cell and sampling system to perform simultaneous spiked and unspiked measurements. The optical configurations shall be similar, if possible. The sampling configurations shall be the same. One sampling system and FTIR analyzer shall be used to measure spiked effluent. The other sampling system and FTIR analyzer shall be used to measure unspiked flue gas. Both systems shall use the same sampling procedure (i.e., batch or continuous).
13.3.1If batch sampling is used, synchronize the cell evacuation, cell filling, and collection of spectra. Fill both cells at the same rate (in cell volumes per unit time).
13.3.2If continuous sampling is used, adjust the sample flow through each gas cell so that the same number of cell volumes pass through each cell in a given time (i.e. TC1 = TC2).
13.4Statistical Treatment. The statistical procedure of EPA Method 301 of this appendix, section 6.3 is used to evaluate the bias and precision. For FTIR testing a validation “run” is defined as spectra of 24 independent samples, 12 of which are spiked with the analyte(s) and 12 of which are not spiked.
13.4.1Bias. Determine the bias (defined by EPA Method 301 of this appendix, section 6.3.2) using equation 7:
Where:
B = Bias at spike level.
Sm = Mean concentration of the analyte spiked samples.
CS = Expected concentration of the spiked samples.
13.4.2Correction Factor. Use section 6.3.2.2 of Method 301 of this appendix to evaluate the statistical significance of the bias. If it is determined that the bias is significant, then use section 6.3.3 of Method 301 to calculate a correction factor (CF). Analytical results of the test method are multiplied by the correction factor, if 0.7 ≤ CF ≤ 1.3. If is determined that the bias is significant and CF > ±30 percent, then the test method is considered to “not valid.”
13.4.3If measurements do not pass validation, evaluate the sampling system, instrument configuration, and analytical system to determine if improper set-up or a malfunction was the cause. If so, repair the system and repeat the validation.
14.0Pollution Prevention
The extracted sample gas is vented outside the enclosure containing the FTIR system and gas manifold after the analysis. In typical method applications the vented sample volume is a small fraction of the source volumetric flow and its composition is identical to that emitted from the source. When analyte spiking is used, spiked pollutants are vented with the extracted sample gas. Approximately 1.6×10−4 to 3.2×10−4 lbs of a single HAP may be vented to the atmosphere in a typical validation run of 3 hours. (This assumes a molar mass of 50 to 100 g, spike rate of 1.0 L/min, and a standard concentration of 100 ppm). Minimize emissions by keeping the spike flow off when not in use.
15.0Waste Management
Small volumes of laboratory gas standards can be vented through a laboratory hood. Neat samples must be packed and disposed according to applicable regulations. Surplus materials may be returned to supplier for disposal.
16.0References
1. “Field Validation Test Using Fourier Transform Infrared (FTIR) Spectrometry To Measure Formaldehyde, Phenol and Methanol at a Wool Fiberglass Production Facility.” Draft. U.S. Environmental Protection Agency Report, EPA Contract No. 68D20163, Work Assignment I-32, September 1994.
2. “FTIR Method Validation at a Coal-Fired Boiler”. Prepared for U.S. Environmental Protection Agency, Research Triangle Park, NC. Publication No.: EPA-454/R95-004, NTIS No.: PB95-193199. July, 1993.
3. “Method 301—Field Validation of Pollutant Measurement Methods from Various Waste Media,” 40 CFR part 63, appendix A.
4. “Molecular Vibrations; The Theory of Infrared and Raman Vibrational Spectra,” E. Bright Wilson, J. C. Decius, and P. C. Cross, Dover Publications, Inc., 1980. For a less intensive treatment of molecular rotational-vibrational spectra see, for example, “Physical Chemistry,” G. M. Barrow, chapters 12, 13, and 14, McGraw Hill, Inc., 1979.
5. “Fourier Transform Infrared Spectrometry,” Peter R. Griffiths and James de Haseth, Chemical Analysis, 83, 16-25,(1986), P. J. Elving, J. D. Winefordner and I. M. Kolthoff (ed.), John Wiley and Sons.
6. “Computer-Assisted Quantitative Infrared Spectroscopy,” Gregory L. McClure (ed.), ASTM Special Publication 934 (ASTM), 1987.
7. “Multivariate Least-Squares Methods Applied to the Quantitative Spectral Analysis of Multicomponent Mixtures,” Applied Spectroscopy, 39(10), 73-84, 1985.
Table 1—Example Presentation of Sampling Documentation
Sample time Spectrum file name Background file name Sample conditioning Process condition
Sample time Spectrum file Interferogram Resolution Scans Apodization Gain CTS Spectrum
Addendum to Test Method 320—Protocol for the Use of Extractive Fourier Transform Infrared (FTIR) Spectrometry for the Analyses of Gaseous Emissions from Stationary Sources
1.0Introduction
The purpose of this addendum is to set general guidelines for the use of modern FTIR spectroscopic methods for the analysis of gas samples extracted from the effluent of stationary emission sources. This addendum outlines techniques for developing and evaluating such methods and sets basic requirements for reporting and quality assurance procedures.
1.1Nomenclature
1.1.1Appendix A to this addendum lists definitions of the symbols and terms used in this Protocol, many of which have been taken directly from American Society for Testing and Materials (ASTM) publication E 131-90a, entitled “Terminology Relating to Molecular Spectroscopy.”
1.1.2Except in the case of background spectra or where otherwise noted, the term “spectrum” refers to a double-beam spectrum in units of absorbance vs. wavenumber (cm−1).
1.1.3The term “Study” in this addendum refers to a publication that has been subjected to EPA- or peer-review.
2.0Applicability and Analytical Principle
2.1Applicability. This Protocol applies to the determination of compound-specific concentrations in single- and multiple-component gas phase samples using double-beam absorption spectroscopy in the mid-infrared band. It does not specifically address other FTIR applications, such as single-beam spectroscopy, analysis of open-path (non-enclosed) samples, and continuous measurement techniques. If multiple spectrometers, absorption cells, or instrumental linewidths are used in such analyses, each distinct operational configuration of the system must be evaluated separately according to this Protocol.
2.2Analytical Principle
2.2.1In the mid-infrared band, most molecules exhibit characteristic gas phase absorption spectra that may be recorded by FTIR systems. Such systems consist of a source of mid-infrared radiation, an interferometer, an enclosed sample cell of known absorption pathlength, an infrared detector, optical elements for the transfer of infrared radiation between components, and gas flow control and measurement components. Adjunct and integral computer systems are used for controlling the instrument, processing the signal, and for performing both Fourier transforms and quantitative analyses of spectral data.
2.2.2The absorption spectra of pure gases and of mixtures of gases are described by a linear absorbance theory referred to as Beer's Law. Using this law, modern FTIR systems use computerized analytical programs to quantify compounds by comparing the absorption spectra of known (reference) gas samples to the absorption spectrum of the sample gas. Some standard mathematical techniques used for comparisons are classical least squares, inverse least squares, cross-correlation, factor analysis, and partial least squares. Reference A describes several of these techniques, as well as additional techniques, such as differentiation methods, linear baseline corrections, and non-linear absorbance corrections.
3.0General Principles of Protocol Requirements
The characteristics that distinguish FTIR systems from gas analyzers used in instrumental gas analysis methods (e.g., Methods 6C and 7E of appendix A to part 60 of this chapter) are: (1) Computers are necessary to obtain and analyze data; (2) chemical concentrations can be quantified using previously recorded infrared reference spectra; and (3) analytical assumptions and results, including possible effects of interfering compounds, can be evaluated after the quantitative analysis. The following general principles and requirements of this Protocol are based on these characteristics.
3.1Verifiability and Reproducibility of Results. Store all data and document data analysis techniques sufficient to allow an independent agent to reproduce the analytical results from the raw interferometric data.
3.2Transfer of Reference Spectra. To determine whether reference spectra recorded under one set of conditions (e.g., optical bench, instrumental linewidth, absorption pathlength, detector performance, pressure, and temperature) can be used to analyze sample spectra taken under a different set of conditions, quantitatively compare “calibration transfer standards” (CTS) and reference spectra as described in this Protocol.
Note:
The CTS may, but need not, include analytes of interest). To effect this, record the absorption spectra of the CTS (a) immediately before and immediately after recording reference spectra and (b) immediately after recording sample spectra.
3.3Evaluation of FTIR Analyses. The applicability, accuracy, and precision of FTIR measurements are influenced by a number of interrelated factors, which may be divided into two classes:
3.3.1Sample-Independent Factors. Examples are system configuration and performance (e.g., detector sensitivity and infrared source output), quality and applicability of reference absorption spectra, and type of mathematical analyses of the spectra. These factors define the fundamental limitations of FTIR measurements for a given system configuration. These limitations may be estimated from evaluations of the system before samples are available. For example, the detection limit for the absorbing compound under a given set of conditions may be estimated from the system noise level and the strength of a particular absorption band. Similarly, the accuracy of measurements may be estimated from the analysis of the reference spectra.
3.3.2Sample-Dependent Factors. Examples are spectral interferants (e.g., water vapor and CO2) or the overlap of spectral features of different compounds and contamination deposits on reflective surfaces or transmitting windows. To maximize the effectiveness of the mathematical techniques used in spectral analysis, identification of interferants (a standard initial step) and analysis of samples (includes effect of other analytical errors) are necessary. Thus, the Protocol requires post-analysis calculation of measurement concentration uncertainties for the detection of these potential sources of measurement error.
4.0Pre-Test Preparations and Evaluations
Before testing, demonstrate the suitability of FTIR spectrometry for the desired application according to the procedures of this section.
4.1Identify Test Requirements. Identify and record the test requirements described in sections 4.1.1 through 4.1.4 of this addendum. These values set the desired or required goals of the proposed analysis; the description of methods for determining whether these goals are actually met during the analysis comprises the majority of this Protocol.
4.1.1Analytes (specific chemical species) of interest. Label the analytes from i = 1 to I.
4.1.2Analytical uncertainty limit (AUi). The AUi is the maximum permissible fractional uncertainty of analysis for the ith analyte concentration, expressed as a fraction of the analyte concentration in the sample.
4.1.3Required detection limit for each analyte (DLi, ppm). The detection limit is the lowest concentration of an analyte for which its overall fractional uncertainty (OFUi) is required to be less than its analytical uncertainty limit (AUi).
4.1.4Maximum expected concentration of each analyte (CMAXi, ppm).
4.2Identify Potential Interferants. Considering the chemistry of the process or results of previous studies, identify potential interferants, i.e., the major effluent constituents and any relatively minor effluent constituents that possess either strong absorption characteristics or strong structural similarities to any analyte of interest. Label them 1 through Nj, where the subscript “j” pertains to potential interferants. Estimate the concentrations of these compounds in the effluent (CPOTj, ppm).
4.3Select and Evaluate the Sampling System. Considering the source, e.g., temperature and pressure profiles, moisture content, analyte characteristics, and particulate concentration), select the equipment for extracting gas samples. Recommended are a particulate filter, heating system to maintain sample temperature above the dew point for all sample constituents at all points within the sampling system (including the filter), and sample conditioning system (e.g., coolers, water-permeable membranes that remove water or other compounds from the sample, and dilution devices) to remove spectral interferants or to protect the sampling and analytical components. Determine the minimum absolute sample system pressure (Pmin, mmHg) and the infrared absorption cell volume (VSS, liter). Select the techniques and/or equipment for the measurement of sample pressures and temperatures.
4.4Select Spectroscopic System. Select a spectroscopic configuration for the application. Approximate the absorption pathlength (LS′, meter), sample pressure (PS′, kPa), absolute sample temperature TS′, and signal integration period (tSS, seconds) for the analysis. Specify the nominal minimum instrumental linewidth (MIL) of the system. Verify that the fractional error at the approximate values PS′ and TS′ is less than one half the smallest value AUi (see section 4.1.2 of this addendum).
4.5Select Calibration Transfer Standards (CTS's). Select CTS's that meet the criteria listed in sections 4.5.1, 4.5.2, and 4.5.3 of this addendum.
Note:
It may be necessary to choose preliminary analytical regions (see section 4.7 of this addendum), identify the minimum analyte linewidths, or estimate the system noise level (see section 4.12 of this addendum) before selecting the CTS. More than one compound may be needed to meet the criteria; if so, obtain separate cylinders for each compound.
4.5.1The central wavenumber position of each analytical region shall lie within 25 percent of the wavenumber position of at least one CTS absorption band.
4.5.2The absorption bands in section 4.5.1 of this addendum shall exhibit peak absorbances greater than ten times the value RMSEST (see section 4.12 of this addendum) but less than 1.5 absorbance units.
4.5.3At least one absorption CTS band within the operating range of the FTIR instrument shall have an instrument-independent linewidth no greater than the narrowest analyte absorption band. Perform and document measurements or cite Studies to determine analyte and CTS compound linewidths.
4.5.4For each analytical region, specify the upper and lower wavenumber positions (FFUm and FFLm, respectively) that bracket the CTS absorption band or bands for the associated analytical region. Specify the wavenumber range, FNU to FNL, containing the absorption band that meets the criterion of section 4.5.3 of this addendum.
4.5.5Associate, whenever possible, a single set of CTS gas cylinders with a set of reference spectra. Replacement CTS gas cylinders shall contain the same compounds at concentrations within 5 percent of that of the original CTS cylinders; the entire absorption spectra (not individual spectral segments) of the replacement gas shall be scaled by a factor between 0.95 and 1.05 to match the original CTS spectra.
4.6Prepare Reference Spectra
Note:
Reference spectra are available in a permanent soft copy from the EPA spectral library on the EMTIC (Emission Measurement Technical Information Center) computer bulletin board; they may be used if applicable.
4.6.1Select the reference absorption pathlength (LR) of the cell.
4.6.2Obtain or prepare a set of chemical standards for each analyte, potential and known spectral interferants, and CTS. Select the concentrations of the chemical standards to correspond to the top of the desired range.
4.6.2.1Commercially-Prepared Chemical Standards. Chemical standards for many compounds may be obtained from independent sources, such as a specialty gas manufacturer, chemical company, or commercial laboratory. These standards (accurate to within ±2 percent) shall be prepared according to EPA Traceability Protocol (see Reference D) or shall be traceable to NIST standards. Obtain from the supplier an estimate of the stability of the analyte concentration. Obtain and follow all of the supplier's recommendations for recertifying the analyte concentration.
4.6.2.2Self-Prepared Chemical Standards. Chemical standards may be prepared by diluting certified commercially prepared chemical gases or pure analytes with ultra-pure carrier (UPC) grade nitrogen according to the barometric and volumetric techniques generally described in Reference A, section A4.6.
4.6.3Record a set of the absorption spectra of the CTS {R1}, then a set of the reference spectra at two or more concentrations in duplicate over the desired range (the top of the range must be less than 10 times that of the bottom), followed by a second set of CTS spectra {R2}. (If self-prepared standards are used, see section 4.6.5 of this addendum before disposing of any of the standards.) The maximum accepted standard concentration-pathlength product (ASCPP) for each compound shall be higher than the maximum estimated concentration-pathlength products for both analytes and known interferants in the effluent gas. For each analyte, the minimum ASCPP shall be no greater than ten times the concentration-pathlength product of that analyte at its required detection limit.
4.6.4Permanently store the background and interferograms in digitized form. Document details of the mathematical process for generating the spectra from these interferograms. Record the sample pressure (PR), sample temperature (TR), reference absorption pathlength (LR), and interferogram signal integration period (tSR). Signal integration periods for the background interferograms shall be ≥tSR. Values of PR, LR, and tSR shall not deviate by more than ±1 percent from the time of recording [R1] to that of recording [R2].
4.6.5If self-prepared chemical standards are employed and spectra of only two concentrations are recorded for one or more compounds, verify the accuracy of the dilution technique by analyzing the prepared standards for those compounds with a secondary (non-FTIR) technique in accordance with sections 4.6.5.1 through 4.6.5.4 of this addendum.
4.6.5.1Record the response of the secondary technique to each of the four standards prepared.
4.6.5.2Perform a linear regression of the response values (dependant variable) versus the accepted standard concentration (ASC) values (independent variable), with the regression constrained to pass through the zero-response, zero ASC point.
4.6.5.3Calculate the average fractional difference between the actual response values and the regression-predicted values (those calculated from the regression line using the four ASC values as the independent variable).
4.6.5.4If the average fractional difference value calculated in section 4.6.5.3 of this addendum is larger for any compound than the corresponding AUi, the dilution technique is not sufficiently accurate and the reference spectra prepared are not valid for the analysis.
4.7Select Analytical Regions. Using the general considerations in section 7 of Reference A and the spectral characteristics of the analytes and interferants, select the analytical regions for the application. Label them m = 1 to M. Specify the lower, center and upper wavenumber positions of each analytical region (FLm, FCm, and FUm, respectively). Specify the analytes and interferants which exhibit absorption in each region.
4.8Determine Fractional Reproducibility Uncertainties. Using appendix E of this addendum, calculate the fractional reproducibility uncertainty for each analyte (FRUi) from a comparison of [R1] and [R2]. If FRUi > AUi for any analyte, the reference spectra generated in accordance with section 4.6 of this addendum are not valid for the application.
4.9Identify Known Interferants. Using appendix B of this addendum, determine which potential interferants affect the analyte concentration determinations. Relabel these potential interferant as “known” interferants, and designate these compounds from k = 1 to K. Appendix B to this addendum also provides criteria for determining whether the selected analytical regions are suitable.
4.10Prepare Computerized Analytical Programs
4.10.1Choose or devise mathematical techniques (e.g, classical least squares, inverse least squares, cross-correlation, and factor analysis) based on equation 4 of Reference A that are appropriate for analyzing spectral data by comparison with reference spectra.
4.10.2Following the general recommendations of Reference A, prepare a computer program or set of programs that analyzes all of the analytes and known interferants, based on the selected analytical regions (section 4.7 of this addendum) and the prepared reference spectra (section 4.6 of this addendum). Specify the baseline correction technique (e.g., determining the slope and intercept of a linear baseline contribution in each analytical region) for each analytical region, including all relevant wavenumber positions.
4.10.3Use programs that provide as output [at the reference absorption pathlength (LR), reference gas temperature (TR), and reference gas pressure (PR)] the analyte concentrations, the known interferant concentrations, and the baseline slope and intercept values. If the sample absorption pathlength (LS), sample gas temperature (TS), or sample gas pressure (PS) during the actual sample analyses differ from LR, TR, and PR, use a program or set of programs that applies multiplicative corrections to the derived concentrations to account for these variations, and that provides as output both the corrected and uncorrected values. Include in the report of the analysis (see section 7.0 of this addendum) the details of any transformations applied to the original reference spectra (e.g., differentiation), in such a fashion that all analytical results may be verified by an independent agent from the reference spectra and data spectra alone.
4.11Determine the Fractional Calibration Uncertainty. Calculate the fractional calibration uncertainty for each analyte (FCUi) according to appendix F of this addendum, and compare these values to the fractional uncertainty limits (AUi; see section 4.1.2 of this addendum). If FCUi >AUi, either the reference spectra or analytical programs for that analyte are unsuitable.
4.12Verify System Configuration Suitability. Using appendix C of this addendum, measure or obtain estimates of the noise level (RMSEST, absorbance) of the FTIR system. Alternatively, construct the complete spectrometer system and determine the values RMSSm using appendix G of this addendum. Estimate the minimum measurement uncertainty for each analyte (MAUi, ppm) and known interferant (MIUk, ppm) using appendix D of this addendum. Verify that (a) MAUi < (AUi)(DLi), FRUi < AUi, and FCUi < AUi for each analyte and that (b) the CTS chosen meets the requirements listed in sections 4.5.1 through 4.5.5 of this addendum.
5.0Sampling and Analysis Procedure
5.1Analysis System Assembly and Leak-Test. Assemble the analysis system. Allow sufficient time for all system components to reach the desired temperature. Then, determine the leak-rate (LR) and leak volume (VL), where VL=LR tSS. Leak volumes shall be ≤4 percent of VSS.
5.2Verify Instrumental Performance. Measure the noise level of the system in each analytical region using the procedure of appendix G of this addendum. If any noise level is higher than that estimated for the system in section 4.12 of this addendum, repeat the calculations of appendix D of this addendum and verify that the requirements of section 4.12 of this addendum are met; if they are not, adjust or repair the instrument and repeat this section.
5.3Determine the Sample Absorption Pathlength
Record a background spectrum. Then, fill the absorption cell with CTS at the pressure PR and record a set of CTS spectra [R3]. Store the background and unscaled CTS single beam interferograms and spectra. Using appendix H of this addendum, calculate the sample absorption pathlength (LS) for each analytical region. The values LS shall not differ from the approximated sample pathlength LS′ (see section 4.4 of this addendum) by more than 5 percent.
5.4Record Sample Spectrum. Connect the sample line to the source. Either evacuate the absorption cell to an absolute pressure below 5 mmHg before extracting a sample from the effluent stream into the absorption cell, or pump at least ten cell volumes of sample through the cell before obtaining a sample. Record the sample pressure PS. Generate the absorbance spectrum of the sample. Store the background and sample single beam interferograms, and document the process by which the absorbance spectra are generated from these data. (If necessary, apply the spectral transformations developed in section 5.6.2 of this addendum). The resulting sample spectrum is referred to below as SS.
Note:
Multiple sample spectra may be recorded according to the procedures of section 5.4 of this addendum before performing sections 5.5 and 5.6 of this addendum.
5.5Quantify Analyte Concentrations. Calculate the unscaled analyte concentrations RUAi and unscaled interferant concentrations RUIK using the programs developed in section 4 of this addendum. To correct for pathlength and pressure variations between the reference and sample spectra, calculate the scaling factor, RLPS using equation A.1,
Calculate the final analyte and interferant concentrations RSAi and RSIk using equations A.2 and A.3,
5.6Determine Fractional Analysis Uncertainty. Fill the absorption cell with CTS at the pressure PS. Record a set of CTS spectra [R4]. Store the background and CTS single beam interferograms. Using appendix H of this addendum, calculate the fractional analysis uncertainty (FAU) for each analytical region. If the FAU indicated for any analytical region is greater than the required accuracy requirements determined in sections 4.1.1 through 4.1.4 of this addendum, then comparisons to previously recorded reference spectra are invalid in that analytical region, and the analyst shall perform one or both of the procedures of sections 5.6.1 through 5.6.2 of this addendum.
5.6.1Perform instrumental checks and adjust the instrument to restore its performance to acceptable levels. If adjustments are made, repeat sections 5.3, 5.4 (except for the recording of a sample spectrum), and 5.5 of this addendum to demonstrate that acceptable uncertainties are obtained in all analytical regions.
5.6.2Apply appropriate mathematical transformations (e.g., frequency shifting, zero-filling, apodization, smoothing) to the spectra (or to the interferograms upon which the spectra are based) generated during the performance of the procedures of section 5.3 of this addendum. Document these transformations and their reproducibility. Do not apply multiplicative scaling of the spectra, or any set of transformations that is mathematically equivalent to multiplicative scaling. Different transformations may be applied to different analytical regions. Frequency shifts shall be less than one-half the minimum instrumental linewidth, and must be applied to all spectral data points in an analytical region. The mathematical transformations may be retained for the analysis if they are also applied to the appropriate analytical regions of all sample spectra recorded, and if all original sample spectra are digitally stored. Repeat sections 5.3, 5.4 (except the recording of a sample spectrum), and 5.5 of this addendum to demonstrate that these transformations lead to acceptable calculated concentration uncertainties in all analytical regions.
6.0Post-Analysis Evaluations
Estimate the overall accuracy of the analyses performed in accordance with sections 5.1 through 5.6 of this addendum using the procedures of sections 6.1 through 6.3 of this addendum.
6.1Qualitatively Confirm the Assumed Matrix. Examine each analytical region of the sample spectrum for spectral evidence of unexpected or unidentified interferants. If found, identify the interfering compounds (see Reference C for guidance) and add them to the list of known interferants. Repeat the procedures of section 4 of this addendum to include the interferants in the uncertainty calculations and analysis procedures. Verify that the MAU and FCU values do not increase beyond acceptable levels for the application requirements. Re-calculate the analyte concentrations (section 5.5 of this addendum) in the affected analytical regions.
6.2Quantitatively Evaluate Fractional Model Uncertainty (FMU). Perform the procedures of either section 6.2.1 or 6.2.2 of this addendum:
6.2.1Using appendix I of this addendum, determine the fractional model error (FMU) for each analyte.
6.2.2Provide statistically determined uncertainties FMU for each analyte which are equivalent to two standard deviations at the 95 percent confidence level. Such determinations, if employed, must be based on mathematical examinations of the pertinent sample spectra (not the reference spectra alone). Include in the report of the analysis (see section 7.0 of this addendum) a complete description of the determination of the concentration uncertainties.
6.3Estimate Overall Concentration Uncertainty (OCU). Using appendix J of this addendum, determine the overall concentration uncertainty (OCU) for each analyte. If the OCU is larger than the required accuracy for any analyte, repeat sections 4 and 6 of this addendum.
7.0Reporting Requirements
[Documentation pertaining to virtually all the procedures of sections 4, 5, and 6 will be required. Software copies of reference spectra and sample spectra will be retained for some minimum time following the actual testing.]
8.0References
(A) Standard Practices for General Techniques of Infrared Quantitative Analysis (American Society for Testing and Materials, Designation E 168-88).
(B) The Coblentz Society Specifications for Evaluation of Research Quality Analytical Infrared Reference Spectra (Class II); Anal. Chemistry 47, 945A (1975); Appl. Spectroscopy 444, pp. 211-215, 1990.
(C) Standard Practices for General Techniques for Qualitative Infrared Analysis, American Society for Testing and Materials, Designation E 1252-88.
(D) “EPA Traceability Protocol for Assay and Certification of Gaseous Calibration Standards,” U.S. Environmental Protection Agency Publication No. EPA/600/R-93/224, December 1993.
Appendix A to Addendum to Method 320—Definitions of Terms and Symbols
A.1Definitions of Terms. All terms used in this method that are not defined below have the meaning given to them in the CAA and in subpart A of this part.
Absorption band means a contiguous wavenumber region of a spectrum (equivalently, a contiguous set of absorbance spectrum data points) in which the absorbance passes through a maximum or a series of maxima.
Absorption pathlength means the distance in a spectrophotometer, measured in the direction of propagation of the beam of radiant energy, between the surface of the specimen on which the radiant energy is incident and the surface of the specimen from which it is emergent.
Analytical region means a contiguous wavenumber region (equivalently, a contiguous set of absorbance spectrum data points) used in the quantitative analysis for one or more analytes.
Note:
The quantitative result for a single analyte may be based on data from more than one analytical region.
Apodization means modification of the ILS function by multiplying the interferogram by a weighing function whose magnitude varies with retardation.
Background spectrum means the single beam spectrum obtained with all system components without sample present.
Baseline means any line drawn on an absorption spectrum to establish a reference point that represents a function of the radiant power incident on a sample at a given wavelength.
Beers's law means the direct proportionality of the absorbance of a compound in a homogeneous sample to its concentration.
Calibration transfer standard (CTS) gas means a gas standard of a compound used to achieve and/or demonstrate suitable quantitative agreement between sample spectra and the reference spectra; see section 4.5.1 of this addendum.
Compound means a substance possessing a distinct, unique molecular structure.
Concentration (c) means the quantity of a compound contained in a unit quantity of sample. The unit “ppm” (number, or mole, basis) is recommended.
Concentration-pathlength product means the mathematical product of concentration of the species and absorption pathlength. For reference spectra, this is a known quantity; for sample spectra, it is the quantity directly determined from Beer's law. The units “centimeters-ppm” or “meters-ppm” are recommended.
Derivative absorption spectrum means a plot of rate of change of absorbance or of any function of absorbance with respect to wavelength or any function of wavelength.
Double beam spectrum means a transmission or absorbance spectrum derived by dividing the sample single beam spectrum by the background spectrum.
Note:
The term “double-beam” is used elsewhere to denote a spectrum in which the sample and background interferograms are collected simultaneously along physically distinct absorption paths. Here, the term denotes a spectrum in which the sample and background interferograms are collected at different times along the same absorption path.
Fast Fourier transform (FFT) means a method of speeding up the computation of a discrete FT by factoring the data into sparse matrices containing mostly zeros.
Flyback means interferometer motion during which no data are recorded.
Fourier transform (FT) means the mathematical process for converting an amplitude-time spectrum to an amplitude-frequency spectrum, or vice versa.
Fourier transform infrared (FTIR) spectrometer means an analytical system that employs a source of mid-infrared radiation, an interferometer, an enclosed sample cell of known absorption pathlength, an infrared detector, optical elements that transfer infrared radiation between components, and a computer system. The time-domain detector response (interferogram) is processed by a Fourier transform to yield a representation of the detector response vs. infrared frequency.
Note:
When FTIR spectrometers are interfaced with other instruments, a slash should be used to denote the interface; e.g., GC/FTIR; HPCL/FTIR, and the use of FTIR should be explicit; i.e., FTIR not IR.
Frequency, v means the number of cycles per unit time.
Infrared means the portion of the electromagnetic spectrum containing wavelengths from approximately 0.78 to 800 microns.
Interferogram, I(σ) means record of the modulated component of the interference signal measured as a function of retardation by the detector.
Interferometer means device that divides a beam of radiant energy into two or more paths, generates an optical path difference between the beams, and recombines them in order to produce repetitive interference maxima and minima as the optical retardation is varied.
Linewidth means the full width at half maximum of an absorption band in units of wavenumbers (cm−1).
Mid-infrared means the region of the electromagnetic spectrum from approximately 400 to 5000 cm−1.
Reference spectra means absorption spectra of gases with known chemical compositions, recorded at a known absorption pathlength, which are used in the quantitative analysis of gas samples.
Retardation, σ means optical path difference between two beams in an interferometer; also known as “optical path difference” or “optical retardation.”
Scan means digital representation of the detector output obtained during one complete motion of the interferometer's moving assembly or assemblies.
Scaling means application of a multiplicative factor to the absorbance values in a spectrum.
Single beam spectrum means Fourier-transformed interferogram, representing the detector response vs. wavenumber.
Note:
The term “single-beam” is used elsewhere to denote any spectrum in which the sample and background interferograms are recorded on the same physical absorption path; such usage differentiates such spectra from those generated using interferograms recorded along two physically distinct absorption paths (see “double-beam spectrum” above). Here, the term applies (for example) to the two spectra used directly in the calculation of transmission and absorbance spectra of a sample.
Standard reference material means a reference material, the composition or properties of which are certified by a recognized standardizing agency or group.
Note:
The equivalent ISO term is “certified reference material.”
Transmittance, T means the ratio of radiant power transmitted by the sample to the radiant power incident on the sample. Estimated in FTIR spectroscopy by forming the ratio of the single-beam sample and background spectra.
Wavenumber, v means the number of waves per unit length.
Note:
The usual unit of wavenumber is the reciprocal centimeter, cm−1. The wavenumber is the reciprocal of the wavelength, λ, when λ is expressed in centimeters.
Zero-filling means the addition of zero-valued points to the end of a measured interferogram.
Note:
Performing the FT of a zero-filled interferogram results in correctly interpolated points in the computed spectrum.
A.2Definitions of Mathematical Symbols. The symbols used in equations in this protocol are defined as follows:
(1) A, absorbance = the logarithm to the base 10 of the reciprocal of the transmittance (T).
(2) AAIim = band area of the ith analyte in the mth analytical region, at the concentration (CLi) corresponding to the product of its required detection limit (DLi) and analytical uncertainty limit (AUi) .
(3) AAVim = average absorbance of the ith analyte in the mth analytical region, at the concentration (CLi) corresponding to the product of its required detection limit (DLi) and analytical uncertainty limit (AUi).
(4) ASC, accepted standard concentration = the concentration value assigned to a chemical standard.
(5) ASCPP, accepted standard concentration-pathlength product = for a chemical standard, the product of the ASC and the sample absorption pathlength. The units “centimeters-ppm” or “meters-ppm” are recommended.
(6) AUi, analytical uncertainty limit = the maximum permissible fractional uncertainty of analysis for the ith analyte concentration, expressed as a fraction of the analyte concentration determined in the analysis.
(7) AVTm = average estimated total absorbance in the mth analytical region.
(8) CKWNk = estimated concentration of the kth known interferant.
(9) CMAXi = estimated maximum concentration of the ith analyte.
(10) CPOTj = estimated concentration of the jth potential interferant.
(11) DLi, required detection limit = for the ith analyte, the lowest concentration of the analyte for which its overall fractional uncertainty (OFUi) is required to be less than the analytical uncertainty limit (AUi).
(12) FCm = center wavenumber position of the mth analytical region.
(13) FAUi, fractional analytical uncertainty = calculated uncertainty in the measured concentration of the ith analyte because of errors in the mathematical comparison of reference and sample spectra.
(14) FCUi, fractional calibration uncertainty = calculated uncertainty in the measured concentration of the ith analyte because of errors in Beer's law modeling of the reference spectra concentrations.
(15) FFLm = lower wavenumber position of the CTS absorption band associated with the mth analytical region.
(16) FFUm = upper wavenumber position of the CTS absorption band associated with the mth analytical region.
(17) FLm = lower wavenumber position of the mth analytical region.
(18) FMUi, fractional model uncertainty = calculated uncertainty in the measured concentration of the ith analyte because of errors in the absorption model employed.
(19) FNL = lower wavenumber position of the CTS spectrum containing an absorption band at least as narrow as the analyte absorption bands.
(20) FNU = upper wavenumber position of the CTS spectrum containing an absorption band at least as narrow as the analyte absorption bands.
(21) FRUi, fractional reproducibility uncertainty = calculated uncertainty in the measured concentration of the ith analyte because of errors in the reproducibility of spectra from the FTIR system.
(22) FUm = upper wavenumber position of the mth analytical region.
(23) IAIjm = band area of the jth potential interferant in the mth analytical region, at its expected concentration (CPOTj).
(24) IAVim = average absorbance of the ith analyte in the mth analytical region, at its expected concentration (CPOTj).
(25) ISCi or k, indicated standard concentration = the concentration from the computerized analytical program for a single-compound reference spectrum for the ith analyte or kth known interferant.
(26) kPa = kilo-Pascal (see Pascal).
(27) LS′ = estimated sample absorption pathlength.
(28) LR = reference absorption pathlength.
(29) LS = actual sample absorption pathlength.
(30) MAUi = mean of the MAUim over the appropriate analytical regions.
(31) MAUim, minimum analyte uncertainty = the calculated minimum concentration for which the analytical uncertainty limit (AUi) in the measurement of the ith analyte, based on spectral data in the mth analytical region, can be maintained.
(32) MIUj = mean of the MIUjm over the appropriate analytical regions.
(33) MIUjm, minimum interferant uncertainty = the calculated minimum concentration for which the analytical uncertainty limit CPOTj/20 in the measurement of the jth interferant, based on spectral data in the mth analytical region, can be maintained.
(34) MIL, minimum instrumental linewidth = the minimum linewidth from the FTIR system, in wavenumbers.
Note:
The MIL of a system may be determined by observing an absorption band known (through higher resolution examinations) to be narrower than indicated by the system. The MIL is fundamentally limited by the retardation of the interferometer, but is also affected by other operational parameters (e.g., the choice of apodization).
(35) Ni = number of analytes.
(36) Nj = number of potential interferants.
(37) Nk = number of known interferants.
(38) Nscan = the number of scans averaged to obtain an interferogram.
(39) OFUi = the overall fractional uncertainty in an analyte concentration determined in the analysis (OFUi = MAX[FRUi, FCUi, FAUi, FMUi]).
(40) Pascal (Pa) = metric unit of stat