An Ultra Performance Liquid Chromatography/tandem mass spectrometric (UPLC-MS/MS) multi-residue method for the simultaneous quantitative determination of tetracycline, chlortetracycline hydrochloride, oxytetracycline hydrochloride and doxycycline hydrochloride in milk has been developed in this work. Liquid-liquid extraction with trichloroacetic acid and McIlvaine buffer was used for the isolation of the selected residues from milk. The sample was centrifuged and solid-phase extraction with an OASIS® HLB extraction column was used to clean up the sample extract. The samples were analysed with the instrument operated in the Multiple Reaction Monitoring acquisition mode. UPLC separation was performed on a reversed-phase C18 column using gradient elution with a mobile phase consisting of acetonitrile and 20 mM formic acid. The tetracycline analytes were detected with a quadrupole mass spectrometer using positive ion electrospray ionisation. The confirmatory method has an acceptable detection limit and was validated according to the European requirements for veterinary drug residues according to Commission Decision 2002/657/ES. The recovery of tetracyclinesfrom milk ranged from 80.2 to 93.8% with relative standard deviation no larger than 7.3% for a concentration of 100 μg·l-1. Furthermore, this analytical method is a useful tool for food safety monitoring and controlling veterinary drug use.
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