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

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, EDA, shifted to less positive potential values, while oxidation potentials EAA and EUA corresponding to AA and UA respectively, moved to more positive values, thereby obtaining effective peak's separations of EAA − EDA = 272 mV and EUA − EDA = 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 μA mM−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%.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Dopamine was determined using a simple carbon paste electrode modified with SDS. ► SDS micelles allowed DA quantification in the presence of ascorbic and uric acid. ► The linearity range was 8–134 μM with a sensitivity of 106.58 ± 0.99 μA mM−1. ► The detection limit was 3.70 ± 0.01 μM. ► DA was quantified on a commercial pharmaceutical sample with 94% of recovery.