Electrochemical methods for simultaneous determination of dopamine and ascorbic acid using cetylpyridine bromide/chitosan composite film-modified glassy carbon electrode

In this work, cetylpyridine bromide (CPB)/chitosan composite film-modified glassy carbon electrode (GCE) is developed for simultaneous determination of dopamine (DA) and ascorbic acid (AA) by differential pulse voltammetry (DPV). At CPB/chitosan composite film-modified GCE, the oxidation peak potential of AA shifts toward less positive potential and the peak current of AA increases greatly, while the oxidation peak potential of DA shifts toward more positive potential and peak current decreases greatly in comparison with that on bare electrode. Therefore, the common overlapped oxidation peaks of AA and DA can be separated completely by using CPB/chitosan composite film-modified electrode. For AA and DA in mixture, one can well separates from the other with potential difference of about 0.3 V, which is large enough to allow determination of one in the presence of the other. Under the optimum conditions, the anodic peak currents ( I pa) of DPV are proportional to the concentration of AA in the range of 1.0 × 10 −5 to 2.0 × 10 −3 M, and to that of DA in the range of 4.0 × 10 −5 to 5.0 × 10 −3 M.