Gas-liquid chromatographic determination of sulfamethazine in swine and cattle tissues.

A gas-liquid chromatographic (GLC) method is described for determining sulfonamide residues in animal tissues, with specificity for 7 sulfonamides. Residues are extracted from tissues with acetone-chloroform, fatty substances are removed, and the sulfonamide residue is methylated with diazomethane in acetone-ether to render it amenable to determination by gas-liquid chromatography on an all-glass column suitable for direct on-column injection and a Ni electron-capture detector. Quantitation is achieved by external standardization. The method has a validated limit of sensitivity of 0.10 ppm with the corresponding control values for all tissues being less than 0.01 ppm. Satisfactory recoveries have been obtained for sulfamethazine in swine and cattle tissues. Specificity for sulfamethazine in the presence of sulfathiazole, sulfaquinoxaline, sulfadimethoxine, sulfabromomethazine, sulfaethoxypyridazine, and sulfachloropyrazine is attained by resolution of the respective methyl derivatives on the GLC column.