Dispersive liquid-liquid microextraction combined with high performance liquid chromatography-DAD detection for the determination of sulfonylurea herbicides in water samples

A new method for the determination of four sulfonylurea herbicides (metsulfuron-methyl, chlorsulfuron, bensulfuron-methyl and chlorimuron-ethyl) in water samples was developed by dispersive liquid-liquid microextraction coupled with high performance liquid chromatography-diode array detector. 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 optimised. Under the optimum conditions, the enrichment factors were in the range between 102 and 216. The linearity of the method was obtained in the range of 1.0-100 ng mL-1 with the correlation coefficients (r) ranging from 0.9982 to 0.9995. The method detection limits were 0.2-0.3 ng mL-1. The proposed method has been successfully applied to the analysis of target sulfonylurea herbicides in river, stream and well water samples with satisfactory results.