茶鲜叶中拟除虫菊酯类农药残留的检测方法

A Novel Method for Determination Pyrethroid Pesticides in Fresh Tea Leaves with GC-μECD

拟除虫菊酯农药用量少,杀虫效果好,广泛应用于茶园害虫的控制,是我国出口茶叶中必检的农药。为实现茶叶生产危害分析关键控制点(HACCP)体系中农药残留的源头控制,提供农残源头监督检验方法依据,避免大量使用农药对茶园土壤环境造成的污染,开发茶鲜叶中菊酯类农药的多残留检测方法有重要的实践意义。本实验用V(石油醚)∶V(丙酮)=1∶1混合溶剂提取,经弗罗里硅土柱层析净化除去干扰物质,采用气相色谱,微电子捕获检测器(μECD)测定茶鲜叶中主要的6种拟除虫菊酯类农药残留量。方法最低检出浓度为0.005～0.01mg/kg;茶鲜叶中拟除虫菊酯农药的添加浓度为0.05、0.2、1.0mg/kg,其回收率在83.6%～104.5%,相对标准偏差(RSD)为2.7%～10.2%,符合农药残留分析要求。

Pyrethroids were used widely in tea cultivation for its low dosage, excellent efficacy, and general safety to users and environment. However, the pyrethroids should be legally inspected in organic tea products. In order to carrying out HACCP system in tea production, supervising pesticides in tea plant, the analysis method of target pesticides in fresh tea leaves need to be established. In this paper, a novel method for determination pyrethroids in fresh tea leaves was proposed. Fresh tea leaf samples were extracted with acetone： n-hexane = 1 ： 1, then cleaned with Florisil column followed by GC- μECD determination. Average recoveries of the six pyrethroids were between 83.6 and 104.5% at three spiking levels 0.05mg/kg, 0.2mg/ kg, 1.0mg/kg. Relative standard deviations （RSDs） were less than 10.2% for all of the recovery tests, limit of lowest detection was 0. 002-0.01mg/kg. The proposed method was easy to perform and could be utilized for monitoring pyrethroids from pesticide residues in fresh tea leaves.