A liquid chromatography-tandem mass spectrometry confirmatory assay for the simultaneous determination of several tetracyclines in milk considering keto-enol tautomerism and epimerization phenomena.

A liquid chromatography-electrospray ionization tandem mass spectrometric (LC-ESI-MS/MS) method for the analysis of several tetracyclines residues in bovine milk has been developed. Milk deproteinization/extraction of samples was performed with acidified acetonitrile. After diluting and purification by solid-phase extraction (SPE), the extracts were injected into the instrument operated in Multiple Reaction Monitoring (MRM) acquisition mode.

Validation of a high-performance liquid chromatographic method with fluorescence detection for the simultaneous determination of tetracyclines residues in bovine milk.

A high-performance liquid chromatography-fluorescence detection method was optimized and validated to determine tetracyclines residues in bovine milk. Post-column derivatization using metal complexation in non-aqueous reagent increased the fluorescence of chelates by a factor up to 2.54 compared to water (signal-to-noise ratio enhancement).