微量QuEChERS/气相色谱质谱法快速测定土壤中15种农药残留

Simultaneous Determination of 15 Pesticides Residue in Soil by Micro-QuEChERS Coupled with Gas Chromatography-Mass Spectrometry

为实现瓜菜种植土壤中常见农药的快速、灵敏测定,以改进的微量QuEChERS(μ-QuEChERS)辅助超声提取法,结合气相色谱质谱(GC-MS)分析,建立了土壤中15种农药残留的同时快速检测方法。土壤中15种农药残留采用含有V(1%乙酸的乙腈)∶V(二氯甲烷)=2∶1的混合溶液提取,上清液经过w(N-丙基乙二胺(PSA))∶w(C18)=3∶1混合吸附剂与无水Na2SO4净化。目标物在TG-5MS弱极性石英毛细管柱进行GC分离,以电子轰击电离源(EI)、选择离子监测(SIM)模式的外标法定量。结果表明,超过13种有机污染物在1.0~1 000μg/L范围内呈良好线性关系,且相关系数(r)均超过0.990。所建方法的检出限(LOD,S/N=3)为0.1~1.2μg/kg,定量限(LOQ,S/N=10)为0.5~4.3μg/kg。3个不同添加浓度(5.0、50、200μg/kg)的回收率在73.2%~114.5%范围内,相对标准偏差(RSD,n=3)在1.1%~11.4%范围内。将所建方法应用到海南南渡江流域瓜菜产区土壤中农药残留检测中,观察到土壤中均含有滴滴涕(DDT)、六六六(BHC),且均存在农药多残留情况(≥7种),其中联苯菊酯检测浓度最高。方法简单、快速且灵敏,有机试剂种类和用量少,适合土壤中15种常见农药多残留的同时、快速、批量检测。

In order to achieve rapid and batch determination of common pesticides in vegetable planting soils,a rapid and sensitive method for simultaneous determination of 15 pesticide residues in soils was established by using gas chromatography-mass spectrometry(GC-MS) coupled with modified micro-QuEChERS(μ-QuEChERS) and assisted ultrasonic extraction.A 1.0 g soil sample was extracted by V(acetonitrile with 1.0% acetic acid)∶V(dichloromethane)=1∶1 after in the presence of 2 mL deionized water.After centrifugation at 4 000 r/min for 5 min,the supernatant was purified by the mixed adsorbent of w(PSA)∶w(C18)=3∶1.After centrifugation and conversion solvents,the targets were separated on a TG-5 MS chromatographic column and quantified by selective ion monitoring(SIM) mode with external standard method.The results showed that the linear was good in the concentration range of 1.0~1 000 μg/L for 13 pesticides with the correlation coefficients of more than 0.990.The limit of detection(LOD,S/N=3) and the limit of quantitation(LOQ,S/N=10) were 0.1~1.2 μg/kg and 0.5~4.3 μg/kg.At the three spiked concentration(5.0,50,200 μg/kg),the recoveries of targets compounds were 73.2%~114.5% with relative standard deviation(RSD,n=3) of 1.1%~11.4%.The method was used to the determination of pesticide residues in 4 soils from Nandu River Basin(Hainan Province).The DDTs and BHCs were occurred in the all soils,and also multi-pesticide residues(≥7 kinds) were observed with the highest concentration of bifenthrin.The method is simple,rapid and sensitive,which is suitable for rapid batch detection of 15 common pesticides in soil.