Monitoring Pesticide Residues in Olive Products: Organophosphorus Insecticides in Olives and Oil

A simple and efficient gas-liquid chromatographic method was used to screen and quantitate residues of azinphos ethyl, chlorpyrifos, diazinon, di-methoate, fenthion, fenthion sulfoxide, methi-dathion, parathion ethyl, and parathion methyl in olive fruit and olive oil. Most olive fruit samples analyzed during 1991-1992 either contained no detectable residues of the insecticides or contained low concentrations of fenthion, dimethoate, and chlorpyrifos. One sample contained fenthion sulfoxide at a level exceeding FAO/WHO Codex Ali-mentarius maximum residue levels (MRL) for total fenthion. Commercially packed oil samples either contained no detectable residues of the insecticides or contained low concentrations of fenthion, fenthion sulfoxide, and chlorpyrifos. More than half of the virgin oil samples collected from individual growers contained no detectable residues. The others contained mostly fenthion and its sulfoxide metabolite. Of the samples analyzed, 13% exceeded Codex MRL for total fenthion residues. These samples were from a monitoring program targeted at produce most likely to contain residues. Refining procedures seem to act as a decontamination technique for oil containing fenthion residues.