Investigation of the electrochemical oxidation of clenbuterol at a porous carbon electrode, and its application to the determination of this β-agonist in bovine hair by liquid chromatography with coulometric detection

At pH 5, clenbuterol is oxidized at potentials > 650 mV to form a radical cation, two of which combine in a head to head manner to form a dimer. A method for the determination of this notably abused β2-adrenergic drug in bovine hair has been developed, utilizing this oxidative response. After alkaline degradation of the hair, the drug was extracted using a simple liquid-liquid extraction based on hexane, with a recovery of 92 ± 3.6%. After evaporation to dryness, the residue is dissolved in mobile phase and the drug analysed by reversed phase liquid chromatography using a mobile phase consisting of methanol-0.1 M ammonium acetate (60:40, vv) with 0.4% sodium dodecyl sulphate adjusted to pH 5 with orthophosphoric acid. Quantitation used a two cell coulometric detector with the first cell being used as a screening electrode and the analytical electrode set at +875 mV.