Highly selective determination of ascorbic acid, dopamine, and uric acid by differential pulse voltammetry using poly(sulfonazo III) modified glassy carbon electrode

A highly selective electrochemical method was developed for the simultaneous determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA) using sulfonazo III film-modified on glassy carbon electrode. The modified electrode showed excellent electrocatalytic activity toward the oxidation of AA, DA, and UA. The calibration curves were obtained with 0.5–1300.0 μmol L−1 AA, 0.05–470.0 μmol L−1 DA, and 0.2–100.0 μmol L−1 UA. Detection limits of 0.17 μmol L−1 AA, 0.03 μmol L−1 DA, and 0.11 μmol L−1 UA were obtained. The influence of various substances on the selectivity of the sensor was studied. The results confirm the high selectivity, good sensitivity, and stability of the modified electrode. Satisfactory results were achieved for the determination of DA, AA, and UA with dopamine injection solution, vitamin C tablets, and human urine samples.