Magnetic titanium oxide nanoparticles for hemimicelle extraction and HPLC determination of organophosphorus pesticides in environmental water

We report on a method for the extraction of organophosphorus pesticides (OPPs) from water samples using mixed hemimicelles and magnetic titanium dioxide nanoparticles (Fe3O4@TiO2) modified by cetyltrimethylammonium. Fe3O4@TiO2 nanoparticles were synthesized by a hydrothermal process and then characterized by scanning electron microscopy and Fourier transform IR spectrometry. The effects of the quantity of surfactant, extraction time, desorption solvent, pH value, extraction volume and reuse of the sorbent were optimized with respect to the extraction of OPPs including chlorpyrifos, dimethoate, and trichlorfon. The extraction method was applied to analyze OPPs in environmental water using HPLC along with UV detection. The method has a wide linear range (100-15,000 ng L-1), good linearity (r > 0.999), and low detection limits (26-30 ng L-1). The enrichment factor is similar to 1,000. The recoveries (at spiked levels of 100, 1,000 and 10,000 ng L-1) are in the range of 88.5-96.7 %, and the relative standard deviations range from 2.4 % to 8.7 %.