Determination of Benzoic Acid and Sorbic Acid in Seasoning by High Performance Liquid Chromatography-Tandem Mass Spectrometry

A high performance liquid chromatography-tandem mass spectrometric(HPLC-MS/MS) method was developed for the determination of benzoic acid and sorbic acid in seasoning.The samples of seasoning were acidified by hydrochloric acid and extracted by diethyl ether for several times.The extract was washed with acidic sodium chloride,then evaporated to dryness.The residue was filtrated with membrane and reserved for analysis after dissolved in 1 mL 90% 0.2 mmol/L NH4OAc(pH 5.0)acetonitrile solution.The conditions of extraction and purification were optimized.The analyte was identified under negative electrospray ionization(ESI-) mode and analyzed quantitatively by the external standard method under the single reaction monitoring(SRM) mode.The calibration curve showed a good linearity in the concentration range of 0.5-5 mg/L with correlation coefficients(r2) more than 0.995.The limits of detection(LODs) of benzoic acid and sorbic acid both were 0.1 mg/kg and their limits of quantitation(LOQs) were 0.4 mg/kg and 0.5 mg/kg,respectively.The recoveries of benzoic acid and sorbic acid were in the ranges of 84%-98% and 82%-96%,respectively,with RSDs less than 3%.Actual test results also showed that the method was simple,sensitive and accurate,and was suitable for the trace determination of benzoic acid and sorbic acid residue in complex matrices.