Multiresidue determination of tetracyclines, sulphonamides and chloramphenicol in bovine milk using HPLC-DAD

A high-performance liquid chromatographic method for the simultaneous determination of tetracycline, oxytetracycline, chlortetracycline, sulfamethazine, sulfaquinoxaline, sulfamethoxazole and chloramphenicol in milk has been developed. The determination of these antimicrobials was carried out using HPLC-DAD with a C18 hybrid column and gradient elution with a mobile phase composed of an aqueous phase of 0.075 mol L−1 sodium acetate, 0.035 mol L−1 calcium chloride and 0.025 mol L−1sodium EDTA, pH 7 and an organic phase of methanol:acetonitrile, 75:25 v/v. Sample preparation involved protein precipitation followed by solid-phase extraction using a polymeric cartridge. The method was validated and applied for the analysis of pasteurised milk samples commercialised in Brazil. The limits of quantitation for all antimicrobials, with the exception of choramphenicol, were below the maximum residue limit, which indicates that the method is appropriate for the determination of these antimicrobials in milk.