Determination of pesticide multi-residues in vegetables and fruits by using the QuEchERS in combination with LC-MS/MS

A screening method is proposed for the determination of 29 kinds of pesticide residues including carbamate,organophosphate,benzimidazole and benzoylurea in fruits and vegetables by the QuEChERS method and liquid chromatography-tandem mass spectrometry(LC-MS/MS).Pesticides interested were extracted from samples with acetonitrile containing 1% acetic acid and simultaneous liquid-liquid partitioning formed by adding anhydrous magnesium sulfate plus sodium acetate following by a simple cleanup step known by dispersive solid-phase extraction.Mixed powders of primary secondary amine(PSA) and C18 combined with little graphitized carbon black(GCB) in some cases were simply mixed with acetonitrile extract.The aliquot is determined by LC-MS/MS using external standard method.The method is reliable and stable that the recoveries of almost all pesticides were in the range from 70% to 119% at the spiked level of 1 μg/kg,5 μg/kg,10 μg/kg into samples,and the RSDs were all below 16%.The linearity of method was good from 1 μg/kg~15 μg/kg,and all LOQs ≤1.176 μg/kg.The method is simple,cheap,rugged with high sensitivity and selective well with no interference,fits the determination needed for the multi-residue in fruits and vegetables.