Simultaneous Determination of Monochlorophthalic Anhydride and Monochlorophthalic Acid in Substrates by High Performance Liquid Chromatography
高效液相色谱法同时测定反应物中的单氯代苯酐及单氯代邻苯二甲酸

A high performance liquid chromatographic method has been developed for the simultaneous determination of 3-chlorophthalic anhydride, 4-chlorophthalic anhydride, 3-chlorophthalic acid and 4-chlorophthalic acid. The operating conditions were a Luna-C18 column at 30 degrees C, methanol-0.15 mol/L ammonium dihydrogen phosphate solution (42:58, v/v) as mobile phase with flow rate of 0.8 mL/min, ultra-violet detection at 240 nm. An external standard method was used. Samples were esterified with absolute ethanol at 80-100 degrees C for 15 min. 3-Chlorophthalic anhydride and 4-chlorophthalic anhydride were respectively converted to two isomers of monochloro-O-carboxyl ethyl benzoate, and the monochlorophthalic acids were not esterified under the reaction conditions. The results demonstrated that the recoveries were 99.1%-101.5%; the relative standard deviations ranged from 0.48% to 0.87%; the linear ranges were 3.12-312.4 mg/L, 2.96-222.3 mg/L, 1.86-186.4 mg/L, 1.41-141.0 mg/L for 3-chlorophthalic anhydride, 4-chlorophthalic anhydride, 3-chlorophthalic acid and 4-chlorophthalic acid, respectively. The method was simple, accurate and fast. The six components could be separated completely in about 20 min.