This International Standard specifies a method for the determination of thiol (mercaptan) sulfur in light distillates, such as gasolines and naphtha fractions, and middle distillate fuels, such as kerosines and gas oils, in the range of 0,000 3 % (m/m) to 0,010 0 % (m/m) (3 mg/kg to 100 mg/kg). Organic sulfur compounds such as sulfides, disulfides and thiophene do not interfere. Elemental sulfur does not interfere at contents less than 0,000 5 % (m/m). Hydrogen sulfide interferes, if not removed as described in 8.2. NOTE For the purposes of this International Standard, the term “% (m/m)” is used to represent the mass fraction of a material