Dispersive solid phase extraction followed by low-toxicity vortex-assisted liquid–liquid microextraction for the determination of organophosphorus pesticides by high-performance liquid chromatography

A simple, rapid and environmentally friendly method for the determination of organophosphorus pesticides (OPPs) in soil and cucumber samples was developed by using dispersive solid phase extraction and low-toxicity vortex-assisted liquid–liquid microextraction (DSPE-LT-VALLME) and high performance liquid chromatography with ultraviolet detection (HPLC-UV). Clean-up of the extract from soil and cucumber was conducted by DSPE using multi-walled carbon nanotubes (MWCNTs) as the sorbent. Parameters that could influence the extraction efficiencies, including the type and volume of extraction solvent, time of the vortex, pH of the sample solution and salt addition, were investigated. The linearity of the method was in the range from 1.0 to 600 ng g−1 with correlation coefficients (r) ranging from 0.9992 to 0.9999. The limits of detection (LODs) were 0.018 to 0.12 ng g−1. The relative standard deviations (RSDs) varied from 1.66% to 3.62% (n = 6), and the enrichment factors (EFs) for the target analytes were in the range of 128–136. Finally, the proposed method has been successfully applied to the determination of target analytes in real samples. The recoveries of the target analytes in soil and cucumber samples were between 83.10% and 101.20%.