茶鲜叶中有机磷农药残留分析

Determination of Organophosphorus Pesticide Residues in Fresh Tea Leaves

为监测茶鲜叶中有机磷农药残留污染状况,应用超声波提取、分散固相萃取净化、气相色谱检测,建立了一种简单、快速测定茶鲜叶中7种有机磷农药(敌敌畏、乐果、毒死蜱、甲基对硫磷、马拉硫磷、杀螟硫磷和三唑磷)残留的分析方法。样品采用φ(乙酸)=1%的乙腈溶液超声提取,乙二胺-N-丙基硅烷、十八烷基硅烷键合硅胶和石墨化炭黑混合吸附剂分散萃取净化,DB-1701毛细管柱程序升温分离,火焰光度检测器测定,基质外标法定量。结果表明,在0.01~4.00 mg·L^(-1)范围内,7种有机磷农药的峰面积与其浓度呈良好的线性关系,相关系数均大于0.998,方法的检出限为0.003 4~0.013 6 mg·kg^(-1),定量限为0.012~0.046 mg·kg^(-1),加标回收率为77.7%~98.2%,相对标准偏差(n=5)为2.4%~8.7%。该方法操作简单、结果可靠、溶剂用量少,对检测条件要求低,适用于茶鲜叶中7种有机磷农药残留的检测。

To investigate the pollution of organophosphorus pesticides in fresh tea leaves,a simple and rapid analytical method was established for simultaneous determination of seven organophosphorus pesticides（ dichlorvos,dimethoate,chlorpyrifos,methyl parathion,malathion,fenitrothion,and triazophos）in fresh tea leaves by ultrasound assisted extraction and dispersive solid phase extraction（ DSPE） coupled with gas chromatography. The samples were ultrasonically extracted with acetonitrile（ containing 1% acetic acid）. Subsequently,the extract was cleaned-up by using primary secondary amine,octadecylsilane bonded silica and graphitized carbon black as adsorbents according to the method of DSPE. Then,the residues were determined by a heated DB- 1701 capillary column with flame photometric detector,and quantified using the matrix- matched external standard method. Good linearities between concentrations and peak areas were achieved in the concentration range of 0. 01- 4. 00 mg·L^-1for target pesticides,with correlation coefficients higher than 0. 998. The average recoveries of target pesticides in fresh tea leaves were 77. 7%- 98. 2% with relative standard deviations（ n = 5） ranging from 2. 4% to 8. 7%.The limits of detection for target organophosphorus pesticides were 0. 003 4- 0. 013 6 mg·kg^-1and the limits of quantification were 0. 012- 0. 046 mg·kg^-1. The method was simple,accurate,solvent saving and without special instrument making it suitable for simultaneous determination of seven organophosphorus pesticides in fresh tea leaves.