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

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.