A High Performance Liquid Chromatographic Method for the Determination of Nine Sulfonamides in Milk

Abstract

A High Performance Liquid Chromatographic (HPLC) method for the determination of sulfadiazine, sulfathiazole, sulfapyridine, sulfamerazine, sulfamethiazole, sulfamethazine, sulfachloropyridazine, sulfadimethoxine, and sulfaquinoxaline in milk is described. Milk (10mL) is extracted three times (50, 40, and 40mL) with chloroform/acetone, the extract evaporated to dryness, and redissolved in 5mL potassium phosphate buffer (1.0 molar, pH 4.4). Hexane (5mL) is added to extract the lipid materials. The aqueous buffer layer containing sulfonamides is passed through a cyclobond-I solid phase extraction (SPE) cartridge and the cartridge is washed with 5mL potassium phosphate buffer. The sulfonamides, which are retained on the cartridge, are then eluted with 4mL aqueous acetonitrile (20% water). The eluent is evaporated to remove acetonitrile and the final volume of the aqueous eluent is made to 4mL with ammonium acetate buffer. The eluent is analyzed by HPLC using a reverse phase column with UV detection at 265nm. The recoveries of individual sulfonamides ranged from 64.0% to 85.9% in samples fortified at 10 and 20ppb levels.