Voltammetric determination terbinafine at carbon paste electrode modified with graphene nanosheets

Abstract

Terbinafine (TER) is a well-known potent antifungal administrated for the oral and topical treatment of mycosessince. The present study introduced a novel graphene (Gr) nanosheet integrated carbon paste electrodes (CPEs) for sensitive voltammetric determination of TER in pharmaceutical formulations and surface water samples. On the surface of the Gr/CPEs, terbinafine recorded an irreversible anodic oxidation peak at 1.11 V following a pure adsorption-controlled reaction mechanism accompanied by the transfer of one-electron/proton as predicted by the molecular orbital calculations, scan rate, and pH studies. Integration of the carbon paste matrix with 7.0% graphene nanostructure improved the sensor performance by about 10 folds through the enhancement of the electroactive surface area and the electrocatalytic effect of graphene towards the electrooxidation of the TER molecule at the electrode surface. Details studies were carried out including the impact of the nature and content of the electrode modifier, pH, and the applied scan rate. The cited sensor showed improved sensitivity within the TER concentration range from 0.17 to 10.8 µg mL−1 with a limit of detection of 0.05µgmL-1. A prolonged operational lifetime with high measurement and fabrication reproducibility was reported. The specificity of the fabricated Gr/CPEs was evaluated in the presence of the TER degradation products and other excipients commonly present in pharmaceutical formulations. The reported improved sensor performance encourages the application of the presented voltammetric sensor for the quantification of TER in pharmaceutical formulations, biological fluids, and residues in surface water samples.