应用QuEChERS前处理法处理样品,气相色谱法测定了蔬菜中30种有机磷农药和7种拟除虫菊酯类农药的残留量。样品用乙腈均质提取,采用混合型固相分散萃取净化,上清液用吹氮法蒸干。残渣分别用二氯甲烷和正己烷溶解定容至0.5 mL后,所得溶液供HP-5MS色谱柱分离,分别用火焰光度检测器检测有机磷农药,电子捕获检测器检测拟除虫菊酯类农药。有机磷农药和拟除虫菊酯类农药质量浓度分别在0.05~1.0 mg·L-1和0.02~0.50 mg·L-1范围内呈线性,有机磷农药的检出限(3S/N)在0.003 7~0.015 7 mg·kg-1之间,拟除虫菊酯农药的检出限(3S/N)在0.000 3~0.001 7 mg·kg-1之间。在两个浓度水平上对方法的回收率作了测定,测得回收率在81.2%~104.7%之间,相对标准偏差(n=6)在3.0%~11.4%之间。

Gas chromatography was applied to the determination of residual amounts of 30 organophosphorus pesticides and 7 pyrethroid pesticides in vegetables with sample pre-treatment by QuEChERS method. The pesticides were separated from vegetable samples by extraction with acetonitrile and the extract was purified by dispersive-SPE. After centrifugation, 2 aliquots (2 mL each) of the supernatant were taken and evaporated to dryness by N2-blowing, and the residues were taken up with 0.5 mL of dichloromethane and n-hexane separately, which were used for separation on HP-5MS chromatographic column. Flame photometric detector was used in the determination for organophosphorus pesticides and electron capture detector was used in the determination for pyrethroid pesticides. Linearity ranges for the 30 organophosphorus pesticides were found same between 0.05-1.0 mg·L-1 with detection limits (3S/N) in the range of 0.003 7-0.015 7 mg·kg-1; linearity ranges for the pyrethroid pesticides were same between 0.02-0.5 mg·L-1 with detection limits (3S/N) in the range of 0.000 3-0.001 7 mg·kg-1. Recovery was tested at 2 different concentration levels and values of recovery found were ranged from 81.2% to 104.7% with RSD′s (n=6) in the range from 3.0% to 11.4%.