Determination of sulfonamides in edible salmon tissue by liquid chromatography with postcolumn derivatization and fluorescence detection.

Fourteen sulfonamides-sulfanilamide, sulfadiazine, sulfathiazole, sulfapyridine, sulfamerazine, sulfamethazine, sulfamethizole, sulfamethoxypyridazine, sulfachloropyridazine, sulfamonomethoxine, sulfadoxine, sulfamethoxazole, sulfadimethoxine, and sulfaquinoxoline-residues of which could be found in aquacultured species, were separated in < 25 min by reversed-phase (C18) liquid chromatography (LC) with gradient elution. Analytes were extracted from edible salmon tissue (muscle and adhering skin) with acetonitrile-2% aqueous acetic acid, isolated with 2 liquid-liquid partitionings, and derivatized with fluorescamine after eluting from the column. The derivatives were detected by fluorescence. Recoveries (n = 4) from coho salmon fortified with sulfonamides at 5, 10, and 20 ng/g tissue averaged 79.7 +/- 7.3, 84.6 +/- 7.7, and 88.2 +/- 7.1%, respectively. Limits of quantitation were 5 ng/g tissue, for sulfanilamide, sulfamethoxypyridazine, and sulfaquinoxoline and 1 ng/g tissue for the remaining sulfonamides.