Purification of clenbuterol-like (beta)2-agonist drugs of new generation from bovine urine and hair by (alpha)1-acid glycoprotein affinity chromatography and determination by gas chromatography-mass spectrometry

The control of illegal use of clenbuterol and other (beta)2-agonist drugs as growth promoters in the European Union countries has led to outlaw practices for synthesizing new concept molecules, showing similar biological activity but not detectable by test methods usually employed to perform the official monitoring programmes. The synthesis schemes of some (beta)2-agonist compounds, formally derived from clenbuterol, were found out by Italian detective authorities. These compounds were synthesised ex novo in our laboratories: then, both their molecular structures and biological activities were characterised. In this paper, we describe different strategies for purifying some (beta)2-agonist drugs of new concept, more hydrophobic than clenbuterol. A two-step clean up procedure, prior to gas chromatography-mass spectrometry analysis, was developed for the multi-residue determination of these (beta)2-agonists from bovine hair and urine. The purification strategy we chose was based on adsorption solid phase extraction and, subsequently, on specific molecular recognition by affinity chromatography. The affinity columns were homemade by coupling bovine (alpha)1-acid glycoprotein, a plasmatic acceptor for basic drugs, to a chromatographic support; their effectiveness for purifying new (beta)2-agonists was discussed. The data about method recoveries and repeatability were also reported.