Abstract: Cu2O-reduced graphene oxide nanocomposite (Cu2O-RGO) was applied to modify glassy carbon electrodes (GCE) in order to determine dopamine (DA). The microstructure of the modified electrodes was characterized by scanning electron microscope (SEM) and X-ray differentiation (XRD). Then the electrochemical reduction conditions for preparing Cu2O-RGO/GCE and the experimental conditions for detecting DA were optimized. The electrochemical behavior of DA on the bare electrode and RGO or Cu2O-RGO modified electrodes was also investigated in pH 3.5 phosphate buffer solution (PBS) by cyclic voltammetry. The results showed that the oxidation peaks of ascorbic acid (AA), DA and uric acid (UA) could be well separated and the peak-to-peak potential separations between DA and AA and UA were 204 and 144 mV, respectively. Moreover, the linear response ranges for the determination of DA were 1 × 10-8–1 × 10-6 mol/L and 1 × 10-6 –8 × 10-5 mol/L and the limit of detection (LOD) was 6.0 × 10-9 mol/L (RSN = 3). The proposed method was further applied to determine DA in dopamine injections and serum with satisfactory results.

Key words: nano-cuprous oxide, reduced graphene oxide, modified electrode, dopamine, electrocatalytic oxidation