Electrochemical behavior of dopamine at a 3,3′-dithiodipropionic acid self-assembled monolayers

Monolayers of 3,3′-dithiodipropionic acid (DTDPA) were prepared on a polycrystalline gold electrode through a self-assembly procedure to produce a gold 3,3′-dithiodipropionic acid self-assembled monolayer (AuDTDPA) modified electrode. The characterization of the AuDTDPA electrode was investigated by cyclic voltammetry and ac impedance using the [Fe(CN)6]3−/4− redox couple. The electrochemical behavior of DA on the modified electrode AuDTDPA was studied by cyclic and square-wave voltammetries, using phosphate buffer as supporting electrolyte. The oxidation peak current for DA increases linearly with concentration in the range of 0.35 × 10−5 to 3.4 × 10−5 mol L−1. The performance of the AuDTDPA modified electrode was evaluated for the electroanalytical determination of dopamine (DA) in a pharmaceutical formulation. The AuDTDPA modified electrode showed a stable behavior and the presence of surface-COOH groups avoided the passivation of the electrode surface during the dopamine oxidation.