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). Overall recoveries ranged from 61 to 115%, with RSD(r) from 5 to 15% (n=54). Detection limits ranged from 5 to 35 microg kg(-1). Limits of quantification were established at 50 microg kg(-1). Decision limits (CCalpha) were 109, 108 and 124 microg kg(-1) and detection capabilities (CCbeta) 119, 117 and 161 microg kg(-1) for oxytetracycline, tetracycline and chlortetracycline, respectively. The method was applied successfully in a national monitoring program.