GC Determination of Residual Amount of Pesticides in Off-season Vegetables

Gas chromatography was applied to the determinations of residual amounts of 5 pesticides(i.e.,chlorpyrifos,chlorfenapyr,bifenthrin,cyhalothrin and cis-cypermethrin) in 2 off-season vegetables(cowpea and bitter gourd).The sample was extracted with acetonitrile,the extract of cowpea obtained was filtered with 0.22 μm membrane and the extract of bitter gourd obtained was purified by Agela Cleanert PestiCarb-SPE solid phase column.By using DB-1 capillary chromatographic column,the 5 pesticides were separated completely.Linearity ranges of 5 pesticides were kept in the same range of 0.01-5.0 mg·L-1.The proposed method was used in the determination of 5 pesticides in substantial samples.Tests for recovery and precision were made by standard addition method at 2 different concentration levels,values of recovery found were in the range of 64.7%-98.8% and values of RSD′s(n=6) were less than 9.0%.