Confirmatory analysis of non-steroidal anti-inflammatory drugs in bovine milk by high-performance liquid chromatography with fluorescence detection

HPLC with fluorescence detection is considered for confirmatory analysis of group B veterinary drugs by the European Union legislation. A procedure for confirming the presence of anti-inflammatory non-steroidal drug (NSAID) residues in bovine milk by reversed phase high-performance liquid chromatography with fluorescence detection is herein described. The native fluorescence of nine drugs belonging to different NSAID sub-classes, namely flurbiprofen, carprofen, naproxen, vedaprofen, 5-hydroxy-flunixin, niflumic acid, mefenamic acid, meclofenamic acid and tolfenamic acid, allowed for detection in bovine milk down to 0.25–20.0 μg/kg. Confirmation of the nine NSAIDs is attained by fluorescence detection at characteristic excitation and emission wavelengths. The procedure described is simple and selective. Limits of quantification (LOQs) ranging between 0.25 and 20 μg/kg were measured; satisfactory trueness and within-laboratory reproducibility data were calculated at LOQ spiking levels, apart from 5-hydroxy-flunixin. The procedure developed is used in our laboratory for confirmation of each one of the above mentioned NSAIDs in bovine milk, to support results after HPLC quantitative analysis with UV–vis detection.