Determination of 19 Pyrethroid Pesticides Residues in Mixed Foods by GC-MS with Polar-interval-arrangement Purification

A new method of gas chromatography-mass spectrometry(GC-MS) with polar-interval-arrangement purification was developed for the determination of the residual amounts of 19 pyrethroid pesticides in mixed foods,e.g.dumpling with pork and celery,meat bun and mixed vegetable.The pyrethroid pesticides residues were extracted from homogenized tissue with ethyl acetate-acetonitrile(1∶9,by volume).The extract was cleaned up with Envi-18 and Florisil solid phase extraction columns,and concentrated with the rotary evaporator.The residues were dissolved with n-hexane prior to GC-MS analysis.The analysis of targeted compounds was performed by external standard method under selected ion monitoring(SIM) mode.The method was convenient and rapid.Under the optimal conditions,the quantification limits of the method(S/N≥10) for allethrin,cyfluthrin and cypemethrin were 0.02 mg/kg,while those for other pyrethroid pesticides were less than 0.01 mg/kg.The spiked recoveries of 19 pyrethroid pesticides at three concentration levels of 0.01,0.02,0.1 mg/kg were in the range of 76%-128% with relative standard deviations of 3.8%-14.7%.