气相色谱法测定茶叶中拟除虫菊酯及硫丹类杀虫剂残留量

GC Determination of Residual Amounts of Pyrethroid and Endosulfan Insecticides in Tea

应用气相色谱法对茶叶中拟除虫菊酯及硫丹类杀虫剂残留量作快速测定。用正己烷-丙酮（1＋1）混合溶剂提取样品中的杀虫剂，残渣用正己烷一乙酸乙酯（1＋1）混合溶剂溶解。此溶液先后经凝胶渗透色谱和固相萃取法进行纯化，固相萃取系ENVI-Carb柱和氟罗里硅土固相萃取柱连续净化。以正己烷-乙酸乙酯（1＋1）混合溶液将杀虫剂从柱上洗脱，所得洗脱液在40℃蒸干，用正己烷溶解残渣，将此溶液引入气相色谱仪测定，测定采用电化学检测器并用外标法定量。共测定了茶叶样品中7种拟除虫菊酯和3种硫丹类杀虫剂，所得响应信号值与杀虫剂浓度在0．01～0．10mg·kg^-1范围呈线性关系，方法的检出限（3S／N）为0．01mg·kg^-1，方法的回收率在87．4％～91．9％之间，测定值的相对标准偏差（n=10）小于7％。

Gas chromatography was used in the rapid determination of residual amounts of pyrethroid and endosulfan insectisides. Insecticides in the sample were extracted with mixture of n-hexane and acetone mixed in the ratio of 1 to 1 by volume, and the residue was dissolved in mixed solvent of n-hexane and ethylacetate （1＋1 by vol. ）. The solution obtained was purified sequentially by gel permeation chromatography and solid phase extraction with ENVI-Carb column and fluorisil column in succession. The eluate in n-hexane-ethyl acetate mixture （1＋1） was evaporated to dryness at 40 ℃, and the residue was dissolved and determined by GC. GC determination of 7 pyrethroids and 3 endosulfans was carried out by external standard method with EC detection. Linear relationship between values of response signal and concentration of the insecticides was obtained in the range of 0. 01- 0. 10 mg·kg^-1, and detection limit （3S/N） of the method found was 0. 01 mg·kg^-1. Tests for recovery and precision were made and values of recovery and RSD＇s （n= 10） found were in the ranges of 87. 4%--91.9% and 7% respectively.