The Use of Bovine Serum Albumin as a Ligand in Affinity Chromatographic Clean-up of Non-Steroidal Anti-Inflammatory Drugs from Bovine Plasma

Abstract

The European Union regulates the use of non-steroidal anti-inflammatory drugs (NSAID) in animal production and official national analytical monitoring programmes have been set up in each member state to detect residues of the drugs in bovine plasma. In this work, we describe the development and application of affinity chromatography for molecular recognition of NSAID in bovine plasma. Bovine serum albumin (BSA), the plasma protein which binds such drugs, was covalently bound to a polymeric support via its glycosyl moieties. Loading capacities and specificity were tested both on standard solutions and on spiked bovine plasma for nine drugs—ketoprofen, naproxen, phenylbutazone, oxyphenylbutazone, acetylsalicylic acid, salicylic acid, tolfenamic acid, diclofenac, and nimesulide—chosen as being the most representative of the different chemical sub-classes of NSAID. The BSA columns could bind up to 150 × 10⁻⁶ g total of a mixture of these nine NSAID, with mean recoveries ranging from 74.0% (tolfenamic acid) to 96.0% (nimesulide). HPLC separation on an RP C₁₈ column with a linear gradient enabled resolution of the drugs; identification was achieved by coupling with photodiode array detection (DAD) operated at 240 and 280 nm. Results showed that all the compounds except acetylsalicylic acid were bound effectively by the BSA affinity columns. When plasma samples were spiked at 2.5 μg mL⁻¹ with a mixture of the NSAID the chromatographic profile and UV spectra recorded (in the range 220–350 nm) indicated the procedure was sufficiently selective for identification of the drugs at the concentrations expected according to their pharmacokinetics. No memory effects and matrix interferences were observed.