气相色谱法测定茶叶中3种有机氯和16种拟除虫菊酯农药残留

Determination of 3 organic cholorine and 16 pyrethroid pesticide residues in tea by GC

目的建立茶叶中3种有机氯和16种拟除虫菊酯农药残留的毛细管气相色谱测定方法。方法茶叶经过研磨后准确称取2.0 g,样品加入20 ml乙腈超声、震荡提取,离心后取10 ml上层乙腈溶液,溶液经过旋蒸蒸干后通过Cleanert PC/NH2柱和硅镁柱净化2次,最后使用正己烷定容至1 ml,DM-17石英毛细管色谱柱分离,电子俘获检测器（ECD）测定,外标法定量,一次性分析茶叶中19种有机氯类和拟除虫菊酯类农药的残留量。结果 19种农药的分离效果好,线性关系良好,平均回收率在65%~123%之间,RSD在2.5%~7.3%之间,本实验具有较好的回收率和精密度,可以满足实际检测需求。结论该方法快速、简便,准确度和精密度良好,可用于茶叶中多种有机氯和拟除虫菊酯农药残留的测定。

Objective The purpose of the test was to establish a method for determination of 3 organic cholorine and 16 pyre- throid pesticide residues in tea by GC. Methods Tea were ground and weighed 2.0 g. Then samples were extracted with ace- tonitrile 20ml by ultrasonic and oscillation. Subsequently, collected supernatant 10 ml after centrifugation. Supernatants were evaporated and purified by CleanertPC/NH2 column and silicon magnesium column. The residues were dissolved to constant volume 1 ml with n -hexane, and then seperated with DM -17 quartz capillary chromatographic column, and detected with electron capture detector （ECD）. The external standard method was used for quantitative. The residual quantity of 19 organic cholorine and pyrethroid pesticide can be detected at the same time. Results The 19 kinds of pesticides were separated from each other very well. Good linearities were obtained. The average recovery rates were 65% ~ 123% and the relative standard derivation（RSD） was from 2.5% ~ 7.3%. The results of recovery and precision are good. This experiment can achieve the actual testing requirements. Conclusion This method is simple, rapid, accurate and reliable. It can be applied to determine multi - residues of organic chlorine and pyrethroid pesticide in tea.