Validation of a liquid chromatography with ultraviolet detection methodology for the determination of sulfonamides in bovine milk according to 2002/657/EC

Sulfonamides are one class of antimicrobial agents used in milk production. Sulfonamides are often overused because they are inexpensive and readily available. Their presence at a concentration above the limit value is a potential hazard to human health. Brazilian authorities have included in the National Regulatory Monitoring Program, the control of the sulfonamides in bovine milk production. A simple, rapid, sensitive and reliable high-performance liquid chromatographic method with ultraviolet detection for the simultaneous determination of three sulfonamides (sulfathiazole, sulfamethazine, sulfadimethoxine) in bovine milk, using sulfapyridine as an internal standard has been developed and validated. The whole procedure was validated according to the Brazilian Regulation 24/2009 (equivalent to European Union Decision 2002/657/EC). This Regulation establishes criteria and procedures for determination of parameters such as decision limit (CCα), detection capability (CCβ), precision, recovery and ruggedness. The CCα was determined at 104.4, 102.2 and 105.0 μg/kg for sulfathiazole, sulfamethazine, and sulfadimethoxine, respectively. CCβ was 108.8, 104.9 and 109.9 μg/kg for sulfathiazole, sulfamethazine, and sulfadimethoxine, respectively. Average recoveries fortified with 50, 100 and 200 μg/kg leads around 100%. A complete statistical analysis was performed on the results obtained and the results indicate that the method is robust when subjected to day-to-day analytical variations.