This method is for determining the acid number of petroleumproducts, petroleum distillates, and other chemicals bypotentiometric titration. Inorganic acids, organic acids,mercaptans and thiophenols respond to this analysis, but theirrespective salts do not; a procedure is also included for sodiumnaphthenate salts. The typical range for acid number detection is0.002 to 5 mg KOH/g of sample, although higher levels can beaccommodated.