Selective sensing of terbinafine hydrochloride using carbon-based electrodes: a green and sustainable electroanalytical method for pharmaceutical products†

Abstract

Terbinafine hydrochloride (TBF) is a broad-spectrum antifungal used to treat various dermatophyte infections affecting the skin, hair, and nails. Accurate, sensitive, and affordable analytical methods are crucial for quantifying this drug. In this study, we report on the use of carbon-based electrodes for the electrochemical determination of TBF in pharmaceutical samples, including raw materials and tablets. Notably, for the first time in the literature, we employ screen-printed carbon electrodes (SPCE) for TBF quantification. Additionally, glassy carbon electrodes (GCE) were used to explore the redox behavior of the analyte. Electrochemical performance was evaluated and compared using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Optimized conditions of supporting electrolyte and scan rate studies revealed that the oxidation of TBF involves an equal exchange of protons and electrons. For the GCE, the oxidation process was found to be irreversible, controlled by both diffusion and adsorption, while for the SPCE, it was irreversible and diffusion-controlled. Square wave voltammetry (SWV) was optimized for both electrodes to enhance sensitivity. For SPCE, the calibration curve ranged from 5 to 100 μg mL⁻¹, with an LOD of 1.48 μg mL⁻¹ using a single drop of sample. The calibration curve for GCE was constructed between 2.5 and 30 μg mL⁻¹, with a limit of detection (LOD) of 0.072 μg mL⁻¹. TBF quantification was performed on raw material samples from various suppliers and tablet forms using external calibration with a recovery range within 90–110%. Analysis of the data reveals that the voltammetric method's accuracy aligns well with the chromatographic approach based on high performance liquid chromatography (HPLC). Furthermore, the proposed methodology demonstrated outstanding sustainability, achieving a score of 0.91 in Green Analytical Chemistry (GAC) criteria. Our novel approach combines high analytical efficiency with a reduced environmental impact, establishing itself as a green, cost-effective, and accurate alternative for TBF sensing.