Determination of Pyrethroid Pesticides in Water Samples by Dispersive Liquid-liquid Microextraction Coupled with GC-MS

The application of the dispersive liquid-liquid microextraction combined with the gas chromatography-mass spectrometry on the determination of three pyrethroid pesticides(bifenthrin,cypermethrin and deltamethrin)in water samples was studied.Several parameters of the extraction procedure,such as the type of extraction and dispersive solvents and their volumes,ionic strength,extraction time,and shaking mode,were optimized by experiments.Under optimum conditions(14 μL chlorobenzene as the extraction solvent,1.0 mL acetonitrile as the dispersive solvent,sonication for 1 min),the enrichment factors of the three pesticides ranged from 318 to 363,and the linearity varied from 0.05~50 μg/L and 0.5~100 μg/L,respectively.The limits of detection(LODs),based on a signal-to-noise ratio(S/N)of 3,varied from 0.002 to 0.04 μg/L.The relative standard deviations(RSDs)ranged from 3.7% to 11.2%(n=6).The relative recovery(RR)in the river water and lake water were between 86.0%~117.0%.