Dispersive liquid-liquid microextraction for the analysis of three organophosphorus pesticides in real samples by high performance liquid chromatography-ultraviolet detection and its optimization by experimental design

A method was developed for analyzing the organophosphorus pesticides Fenitrothion, Diazinon and Ethion in water samples via dispersive liquid-liquid microextraction and high-performance liquid chromatography. Chloroform and methanol were selected as extraction and dispersive solvents, respectively. Extraction and dispersive solvents (and their volumes), the pH of the sample, and salting out effect were optimized to give a calibration plot that is linear in the range from 10 to 4000 ng.mL(-1) Detection limits are 2 ng.mL(-1) for Fenitrothion and 3 ng.mL(-1) for Diazinon and Ethion. The relative standard deviations for six replicate measurements of 500 ng.mL(-1) of the three pesticides are 3.3, 2.2 and 4.1%, respectively.