Gold nanoparticles modified-ITO electrode for the selective electrochemical quantification of dopamine in the presence of uric and ascorbic acids

An indium tin oxide (ITO) electrode modified with gold nanoparticles, having a mean particle diameter of (19.3 ± 1.2) nm, ITO–AuNPs, was used in this work to carry out the determination of dopamine, DA, by means of differential pulse voltammetry, in the presence of a high concentration of two of its main interfering agents: ascorbic, AA, and uric, UA, acids. Both the latter components impair the neurotransmitter’s detection and its subsequent quantification by electrochemical means, due to inherently overlapping oxidation potentials with respect to DA. This constitutes the main impediment towards achieving a successful, electrochemically simple and affordable quantification method. From the analysis of the oxidation peaks’ currents, relevant analytical parameters, for the ITO–AuNPs electrode towards DA quantification, were obtained as follows: a) in the absence of AA and UA a detection limit of (34.97 ± 0.08) μM with a sensitivity of (10.10 ± 0.08) μA mM−1b) in the presence of AA and UA a detection limit of (34.50 ± 0.07) μM with a sensitivity of (17.62 ± 0.15) μA mM−1.