Development and validation of an HPLC confirmatory method for the determination of tetracycline antibiotics residues in bovine muscle according to the European Union regulation 2002/657/EC

A high-performance liquid chromatographic method with diode-array detection, at 351 nm, was developed and validated for the determination of five tetracyclines (TCs): minocycline, tetracycline, oxytetracycline, chlortetracycline, and doxycycline in bovine muscle. Samples were macerated with a buffer solution, centrifuged, and purified using Abselut Nexus SPE cartridges. The separation of the examined TCs was achieved on an Inertsil ODS-3 5 microm, 250 x 4 mm analytical column, at ambient temperature. A multistep gradient elution was followed using 0.05 M oxalic acid and CH3CN, at a flow rate of 1.65 mL/min. The procedure was validated according to the European Union regulation 2002/657/EC determining selectivity, stability, decision limit, detection capability, accuracy, and precision. The results of the validation process demonstrate that the method can be readily applied to European Union statutory veterinary drug residue surveillance programmes. Mean recoveries of TCs from bovine muscle samples spiked at three concentrations (100, 250, and 400 ng/g) were in the range of 98.7-103.3%. Method's LOQ values achieved were 40 microg/kg for MNC, CTC, and DC and 25 microg/kg for OTC and TC. The decision limits (CCalpha) were in the range of 104.7-109.8 microg/kg, while the detection capability (CCbeta) was in the range of 108.4-116.7 microg/kg for all compounds.