Electrochemical Investigation of Ofloxacin Using a Functionalized Multi-Walled Carbon Nanotube Paste Electrode

Ofloxacin, a member of the fluoroquinolone class of antibiotics, exhibits broad-spectrum activity against both gram-positive and gram-negative bacteria by inhibiting topoisomerase enzymes. Monitoring the concentration of ofloxacin is crucial in pharmaceutical formulations, biological samples, food products, and environmental matrices. In this study, a novel, simple, selective, and sensitive voltammetric sensor was developed for the detection of ofloxacin in pharmaceutical and real-world samples. A functionalized multi-walled carbon nanotube paste electrode (MWCNTPE) was employed for the electrochemical oxidation and quantification of ofloxacin using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Measurements were carried out in 0.1 M phosphate buffer solution, with a scan rate of 0.1 V/s and a pulse period of 0.1 seconds, following an accumulation time of 60 minutes. Ofloxacin was found to adsorb irreversibly onto the electrode surface, producing a well-defined anodic peak at + 0.85 V. The sensor demonstrated high sensitivity, achieving a detection limit as low as 1×10⁻⁸ M, and exhibited excellent selectivity even in the presence of common interfering ions. Owing to its low cost, ease of preparation, and renewability, the sensor was successfully applied for the determination of ofloxacin in pharmaceutical tablets and biological samples, yielding high recovery rates.