Highly selective determination of ascorbic acid, epinephrine, and uric acid by differential pulse voltammetry using poly(Adizol Black B)-modified glassy carbon electrode

Abstract

A polymerized film of Adizol Black B (ABB) on the surface of glassy carbon (GC) electrode was prepared for the simultaneous determination of ascorbic acid (AA), epinephrine (EP), and uric acid (UA). This new electrode presented an excellent electrocatalytic activity towards the oxidation of AA, EP, and UA by differential pulse voltammetry method. The oxidation peaks of the three compounds were well defined and had the enhanced peak currents. The separation of the oxidation peak potentials for AA–EP and EP–UA were about 180 and 130 mV, respectively. The calibration curves obtained for AA, EP, and UA were in the ranges of 2.0–1,970.0, 0.1–64.0, and 0.1–1,700.0 μmol L–1, respectively. The detection limits (S/N = 3) were 0.01, 0.007, and 0.02 μmol L–1 for AA, EP, and UA, respectively. The diffusion coefficient and the catalytic rate constant for the oxidation reaction of EP at poly(ABB) film-coated GC electrode were calculated as 1.54(±0.10) × 10−4 cm2 s−1 and 4.5 × 103 mol−1 L s−1, respectively. The present method was applied to the determination of EP in pharmaceutical, AA in commercially available vitamin C tablet, and UA in urine samples.