Determination of thiophanate-methyl and chlorotoluron in water samplesby improved single-drop microextraction coupled with high-performanceliquid chromatography

摘要

An improved single-drop microextraction method for the determination of thiophanate-methyl and chlorotoluron in water samples was developed, with analysis by high-performance liquid chromatography-ultraviolet detection (HPLC-UV). Several parameters such as solvent type, salt concentration, stirring rate, extraction time, pH and organic drop volume were investigated. The optimum experimental conditions found were: 20 μL 1-octanol, 10% (w/v) NaCl, 600 rpm stirring rate, 40min extraction time, neutral sample pH and 5mL water sample. Under the optimum conditions, the enrichment factors were 45.3 and 107.0 folds for thiophanate-methyl and chlorotoluron, respectively. The method exhibited a wide linear range (1-100 μg L~(-1)'), reasonable detection limits (0.35 μgL~(-1)) and suitable repeatability (RSD < 9.6%) for both analytes. The proposed method was validated with three real water samples fortified at two levels, and reasonable spiked recoveries were achieved in the range of 84.0% ~ 110.3%. The experimental results indicated that the improved SDME was a simple, reliable and convenient technique and could easily be used for the enrichment of other pollutants.