Sm/UiO-66 Modified Electrode for the Electrochemical Determination of Ethambutol Hydrochloride in Pharmaceutical Formulations and Human Urine

and used as an electrode modifier for detecting ethambutol hydrochloride. The material was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, electro­chemical impedance spectroscopy, energy-dispersive X-ray mapping, X-ray photoelectron spectroscopy and scanning electron microscopy. The electrochemical behaviour of etham­butol at the Sm/UiO-66 modified glassy carbon electrode was examined using cyclic voltam­metry and differential pulse voltammetry. The Sm/UiO-66-modified electrode exhibited a strong electrocatalytic response toward ethambutol oxidation, with a clearly defined anodic peak current. Under optimized conditions, the sensor showed a linear response in the 0.5 to 9.9 µM concentration range with a detection limit of 0.23 µM. The sensor demonstrated excellent repeatability (RSD < 3.5 %, n = 10), stability over one week, and high selectivity against common interfering substances. Notably, the proposed method was successfully applied to determine ethambutol in three pharmaceutical and three human urine samples, with exceptional recoveries. The proposed Sm/UiO-66 modified electrode is a reliable, sensitive, and selective tool for ethambutol analysis. This method can serve as a practical alternative or complementary approach for routine pharmaceutical quality control and therapeutic monitoring in tuberculosis treatment.