Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction for Determination of Organophos-phorus Pesticides in Water Samples by Gas Chromatography-Pulsed Flame Photometric Detection

摘要

A fast and simple method was developed for simultaneous determination of seven organophosphorus pesticides (diazinon, disulfoton, chlorpyrifos. parathion-methyl, fenthion, parathion and quinalphos) with ultrasound-assisted dispersive liquid-liquid microextraction and gas chromatography-flame photometric detection in water samples. Some parameters affecting the extraction efficiency, including the types and volumes of extractant and dispersant. sample pH and ultrasonic time, were systematically evaluated. Under optimum conditions, a mixture of 25 μL tetrachloromethane (extraction solvent) and 0.8 mL acetone (disperser) was rapidly injected into a 5 mL water sample. The mixture was emulsified by ultrasound for 5 min to form a cloudy solution. After centrifuge for 5 min at 3500 rpm, the 1 μL sediment was directly injected for GC-PFPD analysis. The method showed good linearity in the range of 0,1-150 μgL~(-1) with a correlation coefficient between 0.9945-0.9995. Enrichment factors varied from 143 to 374 fold. The limits of detection (LOD) (S/N = 3) and limit of quantification (LOQ) (S/N = 10) were 0.01-0.04 and 0.05-0.1 μgL~(-1), respectively. Recovery studies were carried out at two concentration levels in real samples within the range of 70-110 % and RSD were less than 9.8 % (n = 5).