Determination of 17 pyrethroid pesticide residues in vegetables by gas chromatography-mass spectrometry with negative chemical ionization

A method was established for the determination of 17 pyrethroid pesticide residues in vegetables using QuEChERS(quick,easy,cheap,effective,rugged and safe) clean-up method and gas chromatography-mass spectrometry(GC-MS) with negative chemical ionization(NCI).The pyrethroid pesticides in the sample were extracted with acetonitrile.After QuEChERS clean-up with a mixture of primary secondary amine and graphitized carbon black packings,the extract was analyzed by GC-NCI-MS in selected ion monitoring(SIM) mode.An isotope internal standard of cypermethrin was employed to the quantification.The limits of quantification ranged from 0.02 to 5 μg/kg.The recoveries of the pyrethroid pesticides spiked in three different matrixes(peas,broccoli and Chinese onion green) at four spiked levels of 10,20,30 and 100 μg/kg were from 71.0% to 139.0%,and the relative standard deviations were less than 12.8%.This method can be used as a conclusive evidence method of the 17 pyrethroid pesticide residues in vegetables.