[Determination of 25 organochlorine pesticides in tea by gas chromatography-mass spectrometry].

A high performance gas chromatography-mass spectrometry (GC-MS) method for the determination of 25 organochlorine pesticides in tea has been developed. The samples of tea were extracted with n-hexane-acetone (2: 1, v/v). The extract was purified by using a Florisil column with n-hexane-ethyl acetate (9: 1, v/v) as elution solvent. Chromatographic analysis was performed on a DB-35MS capillary column. Satisfactory separation and sensitivity of 25 organochlorine pesticides were obtained with the proposed method. The analytical results show the working curves for 25 organochlorine pesticides were linear in the range of 0.010 - 0.500 mg/L by GC-MS on selective ion monitoring mode. The recoveries of 25 organochlorine pesticides at spiked levels of 0.01 -0.20 mg/kg were 70.8% - 105.5%, and relative standard deviations (RSDs) were 1.6% - 12.7%. The limits of quantitation were 0.01 mg/kg except that for endosulfan I and endosulfan II that were 0.02 mg/kg.