Abstract

A selective modified glassy carbon electrode based on multiwall carbon nanotubes decorated with MgCr₂O₄ nanoparticles was fabricated and used for the determination of phenazopyridine using differential pulse voltammetry. The electrochemical response of the modified electrode toward phenazopyridine was characterized by different electrochemical methods including differential pulse voltammetry (DPV), cyclic voltammetry (CV), and impedance spectroscopy. The prepared electrode showed an efficient synergic effect on the oxidation of phenazopyridine at pH 6.0. The oxidation peak current was proportional to the concentration of phenazopyridine from 0.05 to 7.5 μmol L⁻¹. The detection limit was 0.025 μmol L⁻¹. The applicability of the method was confirmed with satisfactory results obtained through the assay of phenazopyridine in human plasma, urine samples, and pharmaceuticals.