MICELLAR CHROMATOGRAPHIC PROCEDURE WITH DIRECT INJECTION FOR THE DETERMINATION OF SULFONAMIDES IN MILK AND HONEY SAMPLES

The capability of liquid chromatography with micellar mobile phases of sodium dodecyl sulfate (SDS), of allowing the direct injection of biological fluids into reversed-phase columns, was applied to the determination of sulfonamides in milk and honey samples. The chromatographic behavior of a group of 15 sulfonamides was studied at pH 3.0 where the drugs showed a greater separation space. Acetonitrile was added to the mobile phase to decrease the retention of the most hydrophobic drugs and increase the efficiencies, which yielded a higher resolution. The samples were diluted with 0.10 M SDS to facilitate the solubilization of the matrix compounds and release the protein-bound drugs. The procedure is simple, rapid, and reliable, has a low cost, and permits screening for 11 sulfonamides (sulfacetamide, sulfadiazine, sulfadimethoxine, sulfaguanidine, sulfamerazine, sulfamonomethoxine, sulfanilamide, sulfapyridine, sulfaquinoxaline, sulfathiazole, and sulfisoxazole) with good accuracy and precision. The recoveries found for milk and honey samples spiked with 1 μg/mL of each sulfonamide, calculated from the calibration straight lines obtained in aqueous solution, were in the ranges 87–108% and 72–119% for milk and honey samples, respectively. Limits of detection were close to 0.1 μg/mL for sulfadiazine, sulfadimethoxine, sulfamethizole, sulfamonomethoxine, sulfanil-amide, sulfathiazole, and sulfisoxazole in milk samples and sulfacetamide, sulfamethizole, sulfanilamide, and sulfapyridine in honey samples.