Determination of 185 Pesticide Residues in Nuts by Gas Chromatography Tandem Mass Spectrometry

A multi-residue analytical method was developed for the determination of 185 pesticides in nuts(peanuts,sunflower seeds,walnuts and amonds) by gas chromatography tandem mass spectrometry(GC-MS/MS).The pesticide residues were extracted twice with homogenizer using acetonitrile containing 1% acetic acid.The extract was cleaned up with ENVI-18 tandem PSA solid-phase extractor and analyzed by GC-MS/MS under multiple reaction monitoring(MRM) mode.The limits of detection(LOD,S/N=5) were between 0.02 μg/kg and 526.4 μg/kg,in which the LODs of 81% of the tested pesticides were lower than 10 μg/kg.The limits of quantitation(LOQs,S/N=10) of 185 pesticides were less than the maximum residue limits(MRL).All of the tested pesticides showed good linear relationship(r0.99) between 1 and 83 times of LOQs.The four samples were determined at three spiked levels of 1,2,4 times LOQ.The average recoveries of 86.0% pesticides were between 70% and 110%,and 90.5% pesticides were between 60% and 120%.The RSDs of 82.3% pesticides were less than 10%.This method was simple,sensitive and accurate,and could be used for the routine analysis of pesticide residues in nuts.