Voltammetric study of triazole antifungal agent terconazole on sp3 and sp2 carbon-based electrode materials

Abstract

Terconazole belongs to synthetic triazole antifungal agents, inhibiting biosynthesis of ergosterol or other sterols and thus disrupting cell wall synthesis in fungi. In this study, electrochemical behavior of terconazole was studied for the first time using cyclic voltammetry and differential pulse voltammetry on boron doped diamond electrode (BDD) with different surface treatments leading to O-terminated, H-terminated and polished surfaces, as well as on glassy carbon (GCE) and basal-plane pyrolytic graphite electrodes (PGE). Terconazole is not reducible within the potential window on these electrode materials. It is oxidizable in aqueous solutions in pH range from 2.0 to 12.0 in two steps due to the presence of piperazine ring in its molecule, possessing two redox centers at the tertiary nitrogen atoms, by an ECE mechanism. Optimal conditions were found for determination of terconazole in 0.1 mol L−1 phosphate buffer pH 7.2. Using differential pulse voltammetry, the lowest detection limit of 0.40 μmol L−1 and excellent repeatability (RSD 1.1%) were achieved on O-terminated BDD when in-situ anodic activation was used prior to each scan. This is beneficial in comparison with GCE and PGE; their necessity of ex-situ polishing worsens the signal repeatability (RSD ~ 4%) and detection limits reaching 0.50 μmol L−1 and 1.23 μmol L−1, respectively.