The electrochemical study of varenicline (VAR) was done in a wide pH range (2-12), at boron doped diamond electrode (BDDE), glassy carbon electrode (GCE) and hanging mercury electrode (HMDE), using cyclic (CV), square wave (SW) and adsorptive stripping square wave (AdSSW) voltammetric techniques. Depending on the pH and the type of the working electrode the characteristic electrochemical behavior of varenicline was established. The mechanism of the reduction process was suggested. Based on the obtained results, the new electroanalytical method was developed for its determination in the buffer solutions and plasma samples. By applying a square wave voltammetry (SWV) on BDDE and GCE, at pH 3.5 and 4.0, the linear dependence in plasma samples was achieved within the concentration range from 2×10-6 - 1×10-5 M and 4×10-6 - 1×10-5 M, respectively. Limit of detection (LOD) and limit of quantification (LOQ) were obtained as 7.1×10-7 M and 2.4×10-6 M on BDDE, and 1.0×10-6 M and 3.5×10-6 M on GCE, respectively. The recovery and RSD values obtained for VAR in plasma suggested BDDE electrode to be preferable in comparison with GCE. The accuracy of the voltammetric method was confirmed by the determination of VAR in plasma spiked with Champix® tablets and the results were statistically compared with those obtained with Ultra Performance Liquid Chromatography (UPLC) method, as a reference one.
Keywords: Boron doped diamond electrode, Glassy carbon electrode, Hanging mercury drop electrode, Plasma, Reduction, Varenicline, Electrochemical study, Adsorptive stripping square wave voltammetry, Ultra performance liquid chromatography, Limit of detection, Limit of quantification