GC Determination of Some Residual Insecticides in Fresh Soy Bean

A sensitive GC method for determination of 3 residual insecticides,i.e.,fipronil,chlorfenapyr and indoxacarb,was reported in this paper.The residual insecticides were extracted from the sample with a mixed solvent of acetone and n-hexane (mixed in the ratio of 1 to 1 by volume).Two mL portions of the extract were taken and purified by SPE and elution.Two different SPE micro columns and 2 different solvent mixtures were used in the purification and elution processes,one for determination of fipronil and chlorfenapyr,and the other for determination of idoxacarb.HP-capillary chromatographic column (30 m×320 mm,0.25 μm) and μECD detector as well as the method of external standard were adopted in the GC analysis.Tests for recovery and for precision were made and values of recovery and RSD′s (n=5) obtained were in the ranges of 64.3%-92.8% and 5.3%-10.8%.Lower limits of determination (10S/N) found were 0.5,0.5 and 2.5 μg·kg-1 respectively.