Electrochemical performance of boron-doped diamond electrode in surfactant-containing media for ambroxol determination

Abstract

A novel application of boron-doped diamond electrode is introduced for the determination of ambroxol, a potential antioxidant drug belonging to the expectorant class. The electrochemical oxidation of ambroxol was first investigated by cyclic voltammetry using boron-doped diamond and glassy carbon electrodes in aqueous solutions both with and without the addition of surfactant. The compound was irreversibly oxidized in one/two steps at high positive potentials, resulting in the formation of a couple with a reduction and re-oxidation wave at less positive potentials. Special attention was given to the use of adsorptive stripping voltammetry at a surface of mildly oxidized boron-doped diamond electrode in aqueous solutions over the pH range of 1.0–10.0. Addition of anionic surfactant (sodium dodecylsulfate) to ambroxol-containing electrolyte enhanced the stripping current signal. Using square-wave stripping mode, the drug yielded a well-defined voltammetric response in phosphate buffer pH 2.5 containing 4×10−4M sodium dodecylsulfate at +1.02V (versus Ag/AgCl) (after 30s accumulation at +0.50V). The process could be used to determine ambroxol in the concentration range of 0.05–0.7μM, with a detection limit of 0.010μM (4.2ngmL−1). The suggested method was successfully applied to pharmaceuticals and spiked human urine samples.