Voltammetric dopamine sensor based on a gold electrode modified with reduced graphene oxide and Mn3O4 on gold nanoparticles

The authors describe an amperometric sensor for dopamine (DA) which has a working potential as low as +0.02 V (vs. SCE). It makes use of a nanocomposite consisting of reduced graphene oxide (rGO) and manganic manganous oxide (Mn3O4) in a film of Nafion on gold nanoparticles deposited on a gold electrode. The composite was characterized by X-ray powder diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FE-SEM). The electrochemical properties of the modified electrode were investigated by cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and amperometric methods. After method optimization, the amperogram displays a linear range extending from 1.0 mu mol center dot L-1 to 1.45 mmol center dot L-1 with a limit of detection as low as 0.25 mu mol center dot L-1 (at an S/N ratio of 3). The modified electrode was employed for the determination of DA in injection solution samples with satisfactory results.