Liquid Chromatographic Analysis of Multiple Sulfonamide Residues in Chicken Muscle Using Pre-Column Derivatization and Fluorescence Detection

Abstract

A rapid liquid chromatographic (LC) method is described for the quantitation of sulfadiazine, sulfamethazine, sulfadimethoxine, and sulfaquinoxaline residues in chicken muscle. The sulfonamides are extracted with chloroform, partitioned into hydrochloric acid, and submitted to pre-column derivatization with fluorescamine. LC analysis of the fluorescent derivatives is performed on a C₁₈ column using a mobile phase of acetonitrile /20 mM phosphate buffer pH 4, (34/66, v/v), containing 20 mM octanesulfonate sodium salt. Owing to the sensitivity and selectivity of the fluorescence detection, residue levels of as low as 3 ng/g for sulfadiazine, 4 ng/g for sulfamethazine, 9 ng/g for sulfadimethoxine, and 40 ng/g for sulfaquinoxaline could be readily determined in chicken muscle. Overall recoveries were found to be 77.7±4.8% for sulfadiazine, 84.6±4.2% for sulfamethazine, 92.3±4.1% for sulfadimethoxine, and 82.5±7.0% for sulfaquinoxaline. The linearity of the method was quite acceptable in the range examined (5-100 ng/g for sulfadiazine and sulfamethazine, 15-150 ng/g for sulfadimethoxine, and 50-300 ng/g for sulfaquinoxaline).