Voltammetric Behaviour of Pentoxifylline at Mercury Electrode

Abstract

The voltammetric behaviour of pentoxifylline (1-(5′-oxohexyl)-3,7- dimethylxanthine, PTX) was studied in several supporting electrolytes (Britton-Robinson buffer of pH2-12, 0.1 M NH<inf>3</inf>/NH<inf>4</inf>Cl buffer (pH 9.08), 0.1 M Na<inf>2</inf>B<inf>4</inf>O<inf>7</inf> (pH 9.30), 0.1 M KCl (pH 6.22). At 0.1 M Britton-Robinson buffer (pH 7.46) PTX gives two peaks at -0.150V and -1.524V, respectively. At low pH values (pH < 5.50), the second peak was obscured by the hydrogen evolution while the first peak is well defined at 0.1M KNO<inf>3</inf> supporting electrolyte (pH 6.22). The potential of the second peak is practically pH-independent in the pH range of 6.50-11.00. The peaks (at -0.150V and -1.524V) are attributed to the reduction of Hg(I)-PTX complex and carbonyl group at 5′-oxohexyl moiety of the molecule, respectively. The relationship between peak current of carbonyl group and concentration of PTX is linear in 1.48 × 10-5 -1.34 × 10-4M concentration range in 0.1 M KCl (pH 6.22). It was observed that PTX has adsorption/desorption characteristics. A plausible mechanism is proposed for the electrode reaction of PTX on the mercury electrode.