Extraction and determination of sulfonylurea herbicides in water and soil samples by using ultrasound-assisted surfactant-enhanced emulsification microextraction and analysis by high-performance liquid chromatography.

An ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) with low-density extraction solvents was developed for the extraction of sulfonylurea herbicides from water and soil samples prior to high-performance liquid chromatography coupled with ultraviolet detection (HPLC-UV). In this technique, a surfactant was used as emulsifier which could enhance the dispersion of water-immiscible extraction solvent into aqueous phase and was favorable for the mass-transfer of the analytes from aqueous phase to organic phase. The target analytes were extracted into an extraction phase (Aliquat-336 in 1-octanol) and dispersed in an aqueous solution. After extraction and phase separation, the organic solvent on top of the solution was withdrawn into a syringe and 20 µL of it was injected into a HPLC instrument for analysis. Influential factors in extraction were investigated and optimized. Under optimum experimental conditions, calibration curve was linear in the concentration range from 1 to 100 µg/L, with coefficients of estimation (R(2) values) varying from 0.9928 to 0.9952, and satisfactory repeatabilities (4.7<RSDs%<6.1) were attained. High preconcentration factors were achieved ranging from 103 to 153. Applicability of the method to the extraction of sulfonylurea herbicides from different types of complicated matrices, such as water and soil samples, was studied. The obtained results indicated that the proposed method is efficient, fast and inexpensive for extraction and determination of sulfonylurea herbicides in environmental aqueous and soil samples.