Voltammetric determination of phentolamine mesylate in pharmaceutical formulations at poly (4-aminobenzene sulfonic acid)-modified glassy carbon electrode

A poly (4-aminobenzene sulfonic acid)-modified glassy carbon electrode (p-ABSA/GCE) was fabricated by electropolymerization. It was found that phentolamine mesylate, an effective and important cardiovascular dilatation drug with low redox activity at the glassy carbon electrode (GCE) can produce a sensitive well-defined anodic peak current at p-ABSA/GCE. Investigation indicated that the oxidation of phentolamine at p-ABSA/GCE was one electron/one proton transfer process which was controlled by adsorption. In optimal conditions, the anodic peak current was linear to the concentrations of phentolamine over the range of 5.0 x 10(-7)-1.0 x 10(-5) M with a detection limit of 2.0 x 10(-7) M. The modified electrode showed good stability and reproducibility. The electroanalytical method proposed was successfully applied to the determination of phentolamine mesylate in pharmaceutical formulations.