Comparison of fat retainers in accelerated solvent extraction for the selective extraction of PCBs from fat-containing samples

Five types of fat retainers were investigated for the lipid-free extraction of PCBs from fat-containing matrixes using accelerated solvent extraction: florisil, basic alumina, neutral alumina, acidic alumina, and sulfuric acid-impregnated silica. All of the fat retainers generated fat-free extracts when the fat/fat retainer ratio was 1:40. Sulfuric acid-impregnated silica and florisil were the only retainers that gave completely clear extracts, and the former was the only not to show any reaction when treated with sulfuric acid after the extraction. Using sulfuric acid-impregnated silica as fat retainer, on-line cleanup of fat-containing matrixes was possible, as demonstrated for naturally contaminated fish meal as well as certified cod liver oil (CRM 349).