Determination of 11 Organophosphorus Pesticide Residues in Vegetables by Gas Chromatography and Its Effect on Matrix

In order to establish a gas chromatography method for 11 kinds of pesticide residues in vegetables,the pre-treatment method for vegetables according to the standard of NY/T 761-2008 entitled Determination of organic phosphorus,organic nitrogen,pyrethroid and carbamate pesticide residues in fruits and vegetables was modified.Meanwhile,the effect of vegetable matrix on determination efficiency of pesticide residues was explored.During the determination of pesticide residues,DB-17 capillary separation column and flame photometric detector(FPD) were used.The results indicated that 11 organophosphorus pesticide residues could be effectively separated.The recovery rates of 11 pesticides in cucumber,tomato and ginger with three spiked levels were in the range of 71.2%-117.9%.The relative standard deviation(RSD) was in the range of 2.1% to 11.2%.The detection limit of this method was 0.005-0.060 mg/kg for DB-17 column,and the retention time was 6.396-19.400 min.The calibration curves revealed a good linear relationship with correlation coefficients of more than 0.999.Under the heating at 40 ℃ by N2,the recovery rates of dichlorovos and phorate could be enhanced up to 95.00%-103.3%,respectively.A small amount of impure peaks in cabbage,baby vegetables and Shanghai green,and a large number of matrix peaks in garlic chive could interfere with the detection of pesticide residues.