Analysis of Pyrethroid Pesticides in Water Samples by Dispersive Liquid-liquid Microextraction Coupled with Gas Chromatography
A novel method was developed for the determination of pyrethroid pesticide residues in water samples by dispersive liquid-liquid microextraction(DLLME)coupled with capillary gas chromatography with electron capture detection(GC-ECD).Some important parameters that influence the extraction efficiency,such as the kind of the extraction and disperser solvent,their volume and the extraction time,were investigated.In the method,10.0 μL chlorobenzene and 1.0 mL acetone were rapidly injected into a 5.0-mL water sample.After centrifugation at 5000 r/min for 5 min,the sedimented chlorobenzene phase was directly injected into the GC for analysis.Under the optimum conditions,as high as 708-to 1087-fold enrichment factors were achieved.Using α-benzene hexachloride as the internal standard,a good linear relationship was obtained in the range of 0.8-600 μg/L of the analytes with the correlation coefficients of 0.9990-0.9999 and the detection limits of 0.04-0.10 μg/L(S/N=3),respectively.This method has been successfully applied for the determination of pyrethroid pesticide residues in real water samples(tap,well and river waters)with satisfactory results.The recoveries fell in the range from 76.0% to 116.0% and the relative standard deviations were between 3.1% and 7.2%.The method was proven to be simple and environmental benign with high enrichment factor and low cost.