Determination of organophosphorus pesticide residues in Cilento (Campania, Italy) virgin olive oil by capillary gas chromatography

In this study, the occurrence of 18 organophosphorus pesticide residues in Cilento (Campania, Italy) virgin olive oil was investigated. Sixty-five samples were taken from the major production areas during 1999–2000. In 31 samples, nine organophosphorus pesticides, namely azinphos-ethyl, chlorpyrifos-methyl, diazinon, dimethoate, fenthion, formothion, methidathion, parathion and parathion-methyl were found in concentrations ranging from 0.030 to 0.120 mg/kg. Acefate, carbophenothion, chlorpyrifos, malaoxon, malathion, methamidophos, omethoate, paraoxon-methyl, and pirimiphos-methyl were not detected in any sample. Analysis was carried out using capillary gas chromatography with a Nitrogen/Phosphorus Detector (NPD) detector, after sample extraction with n-hexane and clean-up by a single-step multi-cartridge system. Recoveries of 18 pesticides at three fortification levels (0.5, 1.0 and 2.5 mg/kg) were in the range 82–110%. Only two samples contained dimethoate residue that exceeded the FAO/WHO Codex Alimentarius maximum residue limits (MRLs).