ASTM D 5291, Set of standards Standards suitable for calibration for C,H,N of petroleum products: ASTM D5291grade Acetanilide, 99+% Atropine (sulphate monohydrate), 98.5% Benzoic acid, 99.6% Cystine, 99% Diphenyl, 99% EDTA, 99.0% Imidazol, 99+% N