Determination of organophosphorus pesticides in wheat flour by supercritical fluid extraction and gas chromatography with nitrogen–phosphorus detection

Abstract

Application of supercritical fluid extraction (SFE) for selective isolation of organophosphorus pesticides from a real-world matrix (wheat flour) has been described. The method uses extraction with supercritical carbon dioxide at 206.8 bar and 60°C, followed by quantitation by gas chromatography with nitrogen–phosphorous detection without clean-up of the extracts. Comparison of SFE with a method currently employed for sample preparation (i.e., organic solvent extraction followed by liquid–liquid extraction and gel permeation chromatography clean-up) shows that the SFE technique simplifies the sample preparation step and speeds up the determination of organophosphorus pesticides in flour. Extraction times were 60 min for a 7 g sample size. This technique was able to determine organophosphorus pesticides (ethoprophos, diazinon, chlorpyrifos methyl, fenitrothion, parathion, phenthoate, EPN) in samples at the 10 ng/g level.