Electrochemical quantification of dopamine in the presence of ascorbic acid and uric acid using a simple carbon paste electrode modified with SDS micelles at pH 7

摘要

Dopamine's (DA) electrochemical behavior was studied using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in the presence of ascorbic acid (AA) and uric acid (UA), using a carbon paste electrode (CPE) modified with sodium dodecyl sulfate (SDS) micelles, at pH 7 by a rather simple immersion process. The results proved that in the absence of SDS DA oxidation was diffusion-controlled, whereas when the [SDS] = 5 mM it was adsorption-controlled. Furthermore, in the absence of SDS it was observed that the DA, AA and UA oxidation peaks' potentials fully overlapped. However, when the [SDS] = 5 mM, it became clear that the DA's oxidation peak, E_(DA), shifted to less positive potential values, while oxidation potentials E_(AA) and E_(UA) corresponding to AA and UA respectively, moved to more positive values, thereby obtaining effective peak's separations of E_(AA) - E_(DA) = 272 mV and E_(UA) - E_(DA) = 171 mV. It is shown that the electrochemical determination of dopamine in the presence of both AA and UA using the SDS-modified CPE, displayed usable analytic parameters, namely: a linearity range of 8-134 μM, a sensitivity of 106.58 ± 0.99 μAm M~(-1), a detection limit of 3.70±0.01 μM, and a quantification limit of 12.05 ± 0.04 μM, which made it possible to effect DA's quantification on a commercial pharmaceutical sample with a recovery average of 94%.