40 C.F.R. § 1090.275

(a) Standard for all ethanol denaturant. All ethanol denaturant, certified or uncertified, used to produce DFE must be composed solely of carbon, hydrogen, nitrogen, oxygen, and sulfur.

(b) Standards for certified ethanol denaturant. In addition to the requirements of paragraph (a) of this section, certified ethanol denaturant must meet the following requirements:

(1) Sulfur content per-gallon standard. Maximum 330 ppm. If the certified ethanol denaturant producer represents a batch of denaturant as having a maximum sulfur content less than 330 ppm on the PTD (for example, less than or equal to 120 ppm), then the actual sulfur content must be less than or equal to the stated value.

(2) Denaturant type. Only PCG, gasoline blendstocks, or NGLs may be used to produce certified ethanol denaturant.