Solidification of floating organic drop microextraction combined with gas chromatography-flame photometric detection for the analysis of organophosphorus pesticides in water samples

Abstract

A method based on solidification of floating organic drop microextraction (SFODME) with vortex-assisted (VA) emulsification was proposed for the preconcentration of organophosphorus pesticides (OPPs) in water samples, followed by gas chromatography (GC) with flame photometric detection (GC-FPD). A binary mixed solvent whose density is lower than water was used as an extractant to improve the extraction efficiency of the five target OPPs and avoid the employment of traditional organic solvents that are usually highly toxic and expensive. Moreover, vortex agitation accelerated the dispersion of extraction solvents in aqueous samples. The significant parameters affecting the VA-SFODME of target OPPs were studied in detail and the optimal extraction conditions were established. With the use of tributyl phosphate (TBP) as the internal standard, the limits of detection (S/N = 3) were found to be in the range of 0.12–0.56 μg L⁻¹ for the five target OPPs, and the linear range was from 0.6 μg L⁻¹ to 100 μg L⁻¹. The RSDs of the proposed method were in the range of 5.4–13.9% (n = 7, c = 3 μg L⁻¹) and the enrichment factors varied from 117 to 215-fold. The proposed method was successfully applied to the analysis of five OPPs in East Lake water, well water and rainwater samples, and the recoveries for spiked samples were in the range of 83.7–112%.