Trace determination of organophosphorus pesticides in environmental samples by temperature-controlled ionic liquid dispersive liquid-phase microextraction

This paper described a new approach for the determination of organophosphorus pesticides by temperature-controlled ionic liquid dispersive liquid-phase microextraction prior to high-performance liquid chromatography with ultraviolet detection. Methylparathion and phoxim, two of the typical organophosphorus pesticides, were used as the model analytes for the investigation of the development and application of the new microextraction method. 1-Hexyl-3-methylimidazolium hexafluorophosphate [C6MIM][PF6] was used as the extraction solvent and the factors affecting the extraction efficiency such as the volume Of [C6MIM][PF6], pH of working solutions, extraction time, centrifuging time, dissoluble temperature and salt effect were optimized. Under the optimal extraction conditions, methylparathion and phoxim exhibited good linear relationship in the concentration range of 1-100 ng mL(-1). The detection limits were 0.17 ng mL(-1) and 0.29 ng mL(-1), respectively. Precisions of proposed method (RSDs, n = 6) were 2.5% and 2.7%, respectively. This proposed method was successfully applied in the analysis of four real environmental water samples and good spiked recoveries over the range of 88.2-103.6% were obtained. These results indicated that temperature-controlled ionic liquid dispersive liquid-phase microextraction had excellent application prospect in environmental field. (C) 2008 Elsevier B.V. All rights reserved.