Analysis of chlorpyrifos and chlorpyrifos-methyl residues in multi-environmental media by cloud-point extraction and HPLC

A method based on the cloud point extraction-high performance liquid chromatography (CPE-HPLC) has been developed for simultaneous extraction and quantification of the two pesticides, chlorpyrifos and chlorpyrifos-methyl, in water, soils and food vegetables. The non-ionic PEG-6000 was employed as the extraction solvent. Parameters and variables that affected the cloud point extraction (e.g. equilibration temperature and concentration of Na2SO4) were investigated. The optimal conditions for CPE were presented with 6% (w/v) PEG 6000, 3% (w/v) Na2SO4 and equilibration temperature at 65 °C for 65 min. Under these conditions, the recoveries of chlorpyrifos and chlorpyrifos-methyl spiked in water were 83.2–90.3% (RSD, 1.0–1.7) and 83.9–95.2% (RSD, 1.1–2.1), the recoveries in cabbage vegetable were 87.2–92.2% (RSD, 1.2–2.5) and 83.4–88.2% (RSD, 1.2–4.0), and those in soil were 88.8–100.6% (RSD, 1.7–4.1) and 83.9–92.9% (RSD, 0.9–2.4), respectively. The method presented here was proved to be rapid, efficient, and green for extraction and determination of chlorpyrifos and chlorpyrifos-methyl residues from food and multi-environmental media.