Abstract: A method was developed for the determination of chlorpyrifos and its metabolite3,5,6-trichloro-2-pyridinol (TCP) in vegetables using gas chromatography-tandem mass spectrometry （GC-MS/MS）. The sample was extracted with acetone. After the concentration, TCP was derivatized with N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA). The purification was performed using a florisil solid-phase extraction cartridge. The analyte was detected by triple quadrupole MS in multi-reaction monitoring mode. An internal standard method was used for the quantification of chlorpyrifos, the limit of quantification was 1 μg/kg, and the recoveries were in the range of 75.57%-106.41% with the relative standard deviations (RSDs) of 8.33%-17.58%. An external standard method was used for the quantification of TCP, the limit of quantification was 0.5 μg/kg, and the recoveries were in the range of 69.11%-108.43% with the RSDs of 5.20%-19.42%. The good linear relationships were obtained in the range of 2-100 μg/L for the both target analytes. The method can be applied for the determination of chlorpyrifos and its metabolite in vegetables.

Key words: chlorpyrifos, metabolite, vegetables , gas chromatography-tandem mass spectrometry （GC-MS/MS）