Trace analysis of some organophosphorus pesticides in rice samples using ultrasound-assisted dispersive liquid-liquid microextraction and high-performance liquid chromatography.

An ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of a floating organic drop method followed by high-performance liquid chromatography was developed for the extraction, preconcentration, and determination of trace amounts of organophosphorus pesticides in rice samples. Variables affecting the performance of both steps were thoroughly investigated. Some effective parameters on extraction were studied and optimized. Under the optimum conditions, recoveries for rice sample are in the range of 58.0-66.0%. The calibration graphs are linear in the range of 4-800 μg/kg and, limits of detection and limits of quantification are in the range of 1.5-3 and 4.2-8.5 μg/kg, respectively. The relative standard deviation for 50.0 μg/kg of organophosphorus pesticides in rice sample are in the range of 4.4-5.1% (n = 5). The obtained results show that proposed method is a fast and simple method for the determination of pesticides in cereals.