GC-NCI-MS分析茶叶中17种有机氯和拟除虫菊酯农药残留

建立了茶叶试样中17种农药残留(8种有机氯和9种拟除虫菊酯农药)的气相色谱-负化学离子源-质谱(GC-NCI-MS)联用的分析方法.茶叶试样用V(正己烷)/V(丙酮)=1/1混合提取剂超声提取,经Florisil硅藻土和中性氧化铝混合层析柱净化后,以环氧七氯为内标物,采用GC-NCI-MS的选择离子监测方式(SIM)分析;探讨了茶叶试样的基体诱导色谱响应增强影响所产生的分析误差及其减小的措施,用空白试样基体匹配校准曲线法(MC法)定量分析.当加标质量浓度水平为20，50和200μg/kg时,加标回收率为67.9%~129%,相对标准偏差为1.0%~20%,除氯菊酯农药的检出限为8.3μg/kg外,其余大部分农药的检出限均小于1.0μg/kg,线性范围为10~500μg/kg,相关系数均大于0.996,此方法成功地应用于茶叶试样中痕量农药残留的分析.

Multiresidue Determination of 17 Organochlorine and Pyrethroid Pesticides in Tea by Gas Chromatography-Negative Chemical Ionization-Mass Spectrometry

An analytical multiresidue method for the simultaneous determination of 17 pesticides(8 organochlorines and 9 pyrethroids) in tea was developed.Pesticides were extracted from tea with hexane-acetone(volume ratio is 1∶1) in an ultrasonic bath and cleaned up on a Florisil and neutral alumina column, then were determined by gas chromatography with negative chemical ionization mass spectrometric detection in the selected ion monitoring mode,and with heptachlor epoxide as the internal standard.Spiked blank samples were used as standards to counteract the matrix effect observed in the chromatographic determination.The recovery studies were performed at 20,50 and 200 μg/kg fortification levels for each pesticide,and the recoveries ranged from 67.9% to 129% with a relative standard deviation between 1.0% and 20% for the different pesticides. The detection limit of the method was less than 1.0 μg/kg for most of pesticides except for the permethrin.The developed method was linear over the range assayed,10-500 μg/L,with determination coefficients>0.996.Finally,the developed analytical method was successfully applied to the determination of pesticides in several tea samples.