浓硫酸净化-气相色谱法检测茶叶中α-硫丹和拟除虫菊酯类农药残留

Determinnation of the residues of α-endosulfan and pyrethriods in tea by gas chromatography with sulphuric acid clean-up

建立了一种茶叶中硫丹和5种拟除虫菊酯类农药(联苯菊酯、高效氯氟氰菊酯、氯氰菊酯、溴氰菊酯和氰戊菊酯)残留分析的新方法。样品以乙腈提取,浓硫酸-乙醇净化,毛细管柱气相色谱法(GC-ECD)测定。结果表明:在0.005～0.5 mg/kg添加水平内,4种茶叶样品中α-硫丹和5种拟除虫菊酯农药的添加回收率在81.6%～105.9%之间,相对标准偏差(RSD)为0.52%～13.0%(n=3)。α-硫丹和5种拟除虫菊酯农药在4种茶叶中的定量限(LOQ)均为0.005 mg/kg。本方法杂质干扰少,准确度及灵敏度满足农药残留检测要求,对检测硬件要求低,适用于茶叶中α-硫丹及拟除虫菊酯类农药残留的分析。

A new method for clean-up and determining residues of α-endosulfan and pyrethroids in tea was discussed.The method uses acetonitrile to extract residues of the pesticides in tea samples,followed by clean up using sulphuric acid-ethanol and determination using gas chromatography（GC-ECD）.Average fortified recoveries in samples were found at the range of 81.6%-105.9% at fortified levels from 0.005 mg/kg to 0.5 mg/kg with relative standard deviations of 0.52%-13.0%.The limit of quantification（LOQ） of pyrethriods and for blank α-endosulfan in blank samples was 0.005 mg/kg.No obvious interferences were found by using this method.It needs no special instrument and can meet the requirements of pesticide residue analysis on accuracy,sensitivity and precision.It is suitable for the residue analysis of pyrethriods and α-endosulfan residue in tea.