Miniaturized counter current liquid–liquid extraction for organophosphorus pesticides determination

In the present work, a simple, rapid, sensitive and economical sample pre-treatment technique; miniaturized counter current liquid–liquid extraction was developed for the determination of organophosphorus pesticide (OPP) residue in water samples and compared with conventional dispersive liquid–liquid microextraction. Gas chromatography–flame ionization detector (GC/FID) was used for OPP quantification. Two OPPs (diazinon and malathion) were selected as model compounds and the proposed methods were carried out for their preconcentration from water samples. The presented method was based on dispersive liquid–liquid extraction with methanol containing butyl acetate as a solvent with density lower than water. After phase separation, butyl acetate was injected into the GC/FID instrument. The linearity was obtained in the concentration range of 0.4–1000.0 μg L−1 and correlation coefficients were in the range of 0.999–0.997 for diazinon and malathion, respectively. The limits of detection (LODs), was based on signal-to-noise ratio (S/N) of 0.1 μg L−1 for two pesticides.