Supercritical fluid extraction and clean-up of organochlorine pesticides in Chinese herbal medicine

A method involving the simultaneous extraction and clean-up of 13 organochl orine pesticides (OCPs) from Chinese herbal medicines (CHMs) was developed using supercritical fluid extraction (SFE) followed by gas chromatography-e lectron capture detection and mass spectrometric confirmation. The pesticid es in the study consisted of alpha-, beta-, gamma-, and delta-benzene hexac hloride, heptachlor, aldrin, heptachlor epoxide, endosulfan I, 4,4'-DDE (1, 1-dichloro-2,2-bis(p-chlorophenyl)ethene), dieldrin, endrin, 4,4'-DDD (1,1- dichloro-2,2-bis(p-chlorophenyl)ethane), endosulfan II, 4,4'-DDT (2,2-bis(p -chlorophenyl)1,1,1-trichloroethane), endrin aldehyde, and endosulfan sulfa te. A series of experiments was conducted to optimize the final extraction conditions [pure CO2, 250 atm extraction pressure (1 atm=101 325 Pa), 50 de grees C extraction temperature, 5 min static extraction time, 20 min dynami c extraction time, 2.0-g Florisil sorbent on top of 0.1-g samples, 12-ml n- hexane eluting at 1 ml/min, and a 10-ml extraction vessel]. Florisil sorben t was placed with the sample in the SFE vessel to provide a facile and effe ctive clean-up approach. Mean recoveries of 78-121% with reproducibilities of 5-31% were obtained for the pesticides except for endosulfan II, endosul fan sulfate and endrin aldehyde. The simple and rapid method may be used to determine OCPs in CHMs routinely, and in fact, was used to analyze CHMs so ld in Taiwan. (C) 1999 Elsevier Science B.V. All rights reserved.