Application of dispersive liquid-liquid microextraction combined with high-performance liquid chromatography to the determination of carbamate pesticides in water samples

A rapid and sensitive method has been established for the determination of four carbamate pesticides (carbo-furan, carbaryl, pirimicarb, and diethofencarb) in water samples by using dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography diode array detection. Parameters that affect the extraction efficiency, such as the kind and volume of the extraction and disperser solvent, extraction time, and salt addition, were investigated and optimized. Under the optimum conditions, the enrichment factors were in the range between 101 and 145. The linearity of the method was obtained in the range of 5-500 ng mL(-1) with the correlation coefficients (r) ranging from 0.9978 to 0.9997. The method detection limits were 0.4-1.0 ng mL(-1). The relative standard deviations varied from 4.7% to 6.5% (n=5). The relative recoveries of the four carbamates from water samples at spiking levels of 5.0 and 20.0 ng mL(-1) were 84.0-92.0% and 86.5-94.0%, respectively. The proposed method has been successfully applied to the analysis of target carbamate residues in river, rain, well, and tap water samples with satisfactory results.