Voltammetric detection of hydrochlorothiazide at molybdenum oxide modified screen-printed electrodes

Abstract

Electrochemical oxidation of hydrochlorothiazide (HCT) was investigated both experimentally and theoretically to explore the connection between thermodynamics and the oxidation potential. In this work, screen printed carbon electrodes were modified with molybdenum oxide by means of voltammetry. The modified surfaces demonstrated significant sensitivity toward hydrochlorothiazide detection in pH 2.00–buffered aqueous solutions. The employed method was validated and used for hydrochlorothiazide quantification in commercial drug products. In this work, we presented results of density functional calculations for the standard reduction potential of the HCT (H)2|HCT couple in aqueous solution. After consideration of 20 density functionals with 4 different basis sets, it was found that the hybrid meta functionals provide the most accurate prediction of the reduction potential in comparison with the available experimental data. The reported reduction potential is underestimated with GGA and MGGA and is overestimated with hybrid and meta hybrid functionals. Our results highlighted the importance of including solute-solvent hydrogen bonding effects in the theoretical modeling of redox processes. Keywords: Molybdenum oxide, Hydrochlorothiazide, Screen-printed electrodes, Electrochemical deposition, Density functional theory (DFT).