Determination of Organophosphorus Pesticides in Edible Oils by Dispersive Microextraction Based on Acetonitrile/Water-coated Fe₃O

In the present work, a novel dispersive microextraction technique based on acetonitrile/water-coated Fe₃O₄ was proposed to determine the organophosphorus pesticides (OPP) including phorate, diazinon, chlorpyrifos-methyl, pirimiphos-methyl and chlorpyrifos in edible oils. In the method, acetonitrile coated bare Fe₃O₄ was used as the extractant, Fe₃O₄ served as the supporter of acetonitrile, a trace amount of water acted as a crosslinking agent between acetonitrile and bare Fe₃O₄. The analytes adsorbed A/W-Fe₃O₄ can be easily collected and isolated from the sample solution using a magnet before gas chromatography-mass spectrometry (GC–MS) analysis. Several dominant parameters affecting extraction efficiency were investigated and optimized. Under the optimal conditions, the limits of detection and limits of quantification for the five OPP were 1.1–6.7 and 4.8–18.3 ng/g, respectively. The recoveries in spiked real oil samples were in the range of 63.8–102.7 % with RSD between 4.9 and 14.3 %. The proposed simple, rapid and solvent-saving method was successfully applied to detect OPP in edible oils.