40 CFR § 716.45 - How to report on substances and mixtures.
Section 716.120 lists substances and mixtures, in order by Chemical Abstract Service Registry Number and by alphabetical order. Studies of listed substances and listed mixtures shall be reported as follows:
(b) When two or more substances are listed as a mixture under § 716.120(b), studies of the listed mixture and studies of any mixture known to contain the listed mixture must be reported as studies of the listed mixture.
(1) The substance in aqueous solution.