This standard specifies the requirements, sampling, test methods, inspection rules, signs, labels, packaging, transportation and storage of phthalic anhydride. This standard applies to the product quality inspection of phthalic anhydride. This product is mainly used in industries such as plastics, paints, dyes, and chemical fibers. Molecular formula: CHO Relative molecular mass: 148.12 (according to the international relative atomic mass in 2003).