Total organic compounds
Total organic compounds (TOC), as used in the process vents provisions, means those compounds measured according to the procedures of Method 18 of appendix A-6 to 40 CFR part 60, ASTM D6420-18 (incorporated by reference, see 63.14) may be used in lieu of Method 18, if the target compounds are all known and are all listed in Section 1.1 of ASTM D6420-18 as measurable; ASTM D6420-18 must not be used for methane and ethane; and ASTM D6420-18 may not be used as a total VOC method.