Electrocatalytic oxidation of dopamine, ascorbic acid and uric acid at poly­2,6­diaminopyridine on the surface of carbon nanotubes/gc electrodes

Abstract

The preparation and application of poly-(2,6-diaminopyridine) on the surface of a glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (CNTs) are reported. Cyclic voltammetry was used for both the electrochemical synthesis and characterization of the polymers deposited on GCE. The modified electrode shows a synergic effect of the electrocatalytic properties and high active surface area of both the conducting polymer and carbon nanotubes, giving rise to a remarkable improvement of electrocatalytic oxidation of ascorbic acid (AA), dopamine (DA) and uric acid (UA) with respect to polymer-modified electrodes and CNTs‑modified electrodes. This kind of modified electrode shows and excellent electrocatalytic activity towards the oxidation of AA, DA and UA within the linear range of 2.70 × 10-5-1.83 × 10-3, 8.33 × 10-7-1.00 × 10-5 and 4.16 × 10-6-2.25 × 10-4 mol L-1, respectively, in pH 8.0 (phosphate buffer solution). The ternary mixture, which contains AA, DA and UA, can be well separated from each other at a scan rate of 100 mV s-1 with a potential difference of 184, 147 and 321 mV in differential pulse voltammetry (DPV) between AA and DA, DA and UA, and AA and UA, respectively. This approach is so simple and easy that can be used to selectively detect DA, AA and UA in the presence of each other and also in some real samples.