Rapid sample preparation methods for analysis of residues of sulfamethazine and its N4‐acetyl and desamino metabolites in swine tissue by HPLC

Abstract
Rapid sample preparation methods for the determination of sulfamethazine (SMZ) and its N4-acetyl and desamino metabolites in swine tissues at the 0.1 mg kg−1 level are presented. The methods use sonication-aided extraction with dichloromethane. For SMZ and N4-acetyl SMZ analysis extracts are cleaned up and concentrated on a silica disposable column followed by HPLC on a CP™ Spher C8 column using acetonitrile-sodium acetate buffer as the mobile phase. For desamino-SMZ analysis the extract was cleaned up and concentrated on a Florisil disposable column, followed by HPLC on a Nucleosil 5-CN column after formation of an ion-pair complex with 1-heptanesulfonic acid. For desamino SMZ peak identification by diode-array UV/VIS detection is also described. Mean recoveries from spiked tissue samples were about 87% (muscle) and 76% (kidney) for SMZ and N4-acetyl SMZ and about 70% for desamino SMZ.