Sensitive and specific gas-liquid chromatographic-spectrophotometric screening procedure for trace levels of five sulfonamides in liver, kidney, and muscle tissue.

Free and conjugated sulfonamides are extracted from edible animal tissue with acetone. Carbohydrate is precipitated and removed, and the acetone is evaporated. The residue is transferred to a separatory funnel with ethyl ether and 1N HCl. The acid layer is drawn off and a portion of the 1N HCl is screened, using the Bratton-Marshall reaction. If this portion is positive, the remaining portion is buffered to pH 6.5 and extracted with methylene chloride. The residue is methylated with diazomethane and then acylated with pentafluoropropionic anhydride. The resulting derivatives are detected by gas-liquid chromatography, using electron capture (63Ni) detection and a column packed with 3% OV-17 on Gas-Chrom Q. This method has been validated by recovering sulfathiazole, sulfachloropyrazine, sulfamethazine, sulfadimethoxine, and sulfabromomethazine from liver, kidney, and muscle at levels of 0.1, 0.5, and 1.0 ppm. The 5 sulfonamides were recovered in excess of 60%, with an average mean recovery of 81.5% at the 0.1 ppm level, 79.1% at the 0.5 ppm level, and 76.0% at the 1.0 ppm level.