Voltammetric Determination of the Drug Metronidazole Using a Solid Bismuth Drop Electrode

This paper is dedicated to Prof. Jiří Barek, CSc. on the occasion of his 75ᵗʰ birthday and is published in the series New Perspectives on Analytical Chemistry

Abstract

Solid bismuth drop electrode (SBiDE) is a new working electrode commercially available on the Czech market since 2020 by the company Metrohm. The aim of this work was to verify the applicability of SBiDE for the voltammetric determination of a model organic substance representing electrochemically reducible biologically active compounds, namely, the drug metronidazole (an antibiotic used to treat diseases caused by both Gram-positive and Gram-negative anaerobic bacteria). To the best of our knowledge, this is the very first published research work using SBiDE. Under optimum conditions (Britton-Robinson buffer of pH 12.0 was used as the supporting electrolyte and the working electrode surface was not electrochemically regenerated), a linear calibration dependence of metronidazole was obtained using differential pulse voltammetry (DPV) in the concentration range from 1 to 600 μmol L^–1, with the limits of detection (LOD) and quantification (LOQ) of 0.41 μmol L^–1 and 1.4 μmol L^–1, respectively. Cyclic voltammetry (CV) on SBiDE was used to characterize the electrode process of the irreversible reduction of metronidazole. The newly developed DPV method was also successfully applied for the determination of metronidazole in authentic drinking water samples (LOD = 1.8 μmol L⁻¹ and LOQ = 5.8 μmol L⁻¹) and in various dosage forms (UV-Vis spectrophotometry was used as a comparative analytical method).

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