| 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(r>0.99) 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. |