On the Effect of Surfactants on the Plant-Esterase Method for Testing of Residual Pesticides in Vegetables

Among 5 surfactants (including OP,CTMAB,CPC,SLS and SDS) tested,the anion surfactant,sodium dodecyl sulfate (SDS) was found to have significant enhancement effect on sensitivity and stability of the plant-esterase catalyzed color reaction,which was inhibitated by the presence of organo-phosphorus pesticides.Extent of increasing in sensitivity of the color reaction was found to be about 70%.Various factors affecting the color reaction were studied and optimized.The proposed method was tested for its precision and recovery in the determination of dichlorvos in a sample of Chinese cabbage,and the results of RSD′s (n=6) and average recovery obtained were 0.87% and 111% respectively.