Determination of tetracycline antibiotics in animal tissues of food-producing animals by high-performance liquid chromatography using solid-phase extraction.

A high-performance liquid chromatographic (HPLC) method was developed for the determination of oxytetracycline (OTC), tetracycline (TC) and chlortetracycline (CTC) residues in bovine and porcine muscles. The method involved the homogenization of the sample in EDTA-McIlvaine buffer with added n-hexane and dichloromethane, centrifugation, precipitation of the supernatant using trichloroacetic acid and filtration. Preconcentration on Separcol SI C18 cartridges improved the clean-up and the recovery of tetracyclines that were separated by HPLC using the optimized mobile phase of 0.01 M oxalic acid-acetonitrile-methanol (45:35:20) on a Spherisorb ODS 2 column (250 x 4 mm I.D.). UV detection at 360 nm was applied with a detection limit of about 50 ng/g. The diode-array spectra confirmed the applicability of this method to the study of tetracycline residues in carcasses.