MULTICOLUMN SOLID-PHASE EXTRACTION CLEANUP OF ORGANOPHOSPHORUS AND ORGANOCHLORINE PESTICIDE-RESIDUES IN VEGETABLE-OILS AND BUTTERFAT

Diatomaceous earth columns used with reversed and normal solid phase extraction (SPE) cartridges were evaluated for the quantitative determination of a number of organophosphorus (OP) and organochlorine (OC) pesticide residues in edible vegetable oils and butterfat, An oil or fat sample (about 2 g) in hexane was passed through a diatomaceous earth (Extrelut QE) column and a C-18 bonded silica (ODS) SPE cartridge, resulting in the separation of the pesticides from about 98% of the lipids, The eluate was split in half, with the first portion concentrated into acetone for the determination of OP pesticides by gas chromatography with flame photometric detection (GC-FPD), The other half was passed through an Alumina-N SPE cartridge for additional cleanup of lipid matrix to determine OC pesticides by GC with electron-capture detection (GC-ECD), Average recoveries from fortified samples were greater than 89% for the pesticides studied.