This method is designed primarily for screening residues of DDT and the more common chlorine-containing pesticides in amounts above 5 p.p.m. in fat. The rendered fat sample dissolved in hexane is cleaned up by shaking with strong sulfuric acid, then with a potassium bicarbonate-potassium permanganate solution. After concentration, the solution is treated with dispersed sodium and the resulting inorganic chloride is determined by an automatic coulometric titration.