Adsorptive Stripping Voltammetric Determination of Higenamine on a Boron-Doped Diamond Electrode Improved by the Use of an Anionic Surfactant

Abstract

The present work describes the first electroanalytical investigation and a new voltammetric method for a cheap, rapid and simple determination of higenamine at a surface of mildly-oxidized boron-doped diamond electrode (at +1.6 V during 180 s). The oxidation of compound was strongly dependent on pH. The sensitivity of method was significantly improved in the presence of anionic surfactant, sodium dodecyl sulfate (SDS). The first oxidation peak was chosen for the electroanalytical determination of higenamine due to its higher sensitivity compared to the other two ones. By employing square-wave stripping mode, there was a linear dependence of the oxidation peak current at +0.75 V and higenamine concentration in the range of 0.5-30.0 mg L-1 (1.84 x 10(-6)-1.11 x 10(-4) M), with a detection limit of 0.13 mg L-1 (4.79 x 10(-7) M) in BR buffer pH 2.0 containing 2 x 10(-4) M SDS (after 30 s accumulation at open-circuit condition). As an example, the practical applicability of the proposed method was tested with the quantification of higenamine in the commercial dietary supplement formulations, with results in good agreement to those obtained declared by high-performance liquid chromatography with diode-array detection as a reference method.