Multiresidue method for determination of organophosphorus insecticide residues in fatty processed foods by gel permeation chromatography.

A multiresidue method for quantitative determination of 39 organophosphorus compounds (parent pesticides and their major metabolites) in 7 fatty processed foods is described. Samples are extracted with methylene chloride and cleaned up by automated gel permeation chromatography with a Biobeads SX3 column and a methylene chloride-cyclohexane (15 + 85) eluant. Organophosphorus compounds are quantitated by capillary gas-liquid chromatography with flame photometric detection using OV-1701 and DB-5 columns. Average recoveries from samples fortified at 0.025-1 mg/kg ranged from 50.6% for dichlorvos to 185% for malaoxon. Determination limits were between 0.005 and 0.040 micrograms/mL. Results were confirmed by gas chromatography/mass spectrometry with selected-ion monitoring.