Highly selective detection of trace Cu2+ based on polyethyleneimine-reduced graphene oxide nanocomposite modified glassy carbon electrode

Polyethyleneimine-reduced graphene oxide (PEI-RGO) nanocomposites were synthesized via the nucleophilic substitution reactions between the active amine groups in PEI and the surface-exposed epoxy groups in graphene oxide. The nanocomposites combining with nafion were used as the sensing material for the analysis of trace amount of Cu2+ in solution using differential pulse anodic stripping voltammetry (DPASV) and showed specific electrochemical properties. Various experimental parameters that exert influence on deposition and stripping of metal ions, such as pH values, deposition potential, and deposition time, were optimized. Under the optimized parameters, the stripping peaks response increased linearly with increasing concentration of Cu2+ in the ranges of 1 to 70 μmol/L, which was the general feature of the DPASV method for the application of trace metal ion sensing. The limit of detection (S/N = 3) was estimated to be 0.3 μmol/L for Cu2+ and the sensitivity was down to 0.5274 μA/(μmol/L). More importantly, selective detection toward trace Cu2+ was achieved in the presence of other coexisting interfering metal ions.