Electrochemical sensor based on a nanocomposite prepared from TmPO4 and graphene oxide for simultaneous voltammetric detection of ascorbic acid, dopamine and uric acid

A nanocomposite is described that consists of TmPO4 and graphene oxide (GO) and is used to modify a glassy carbon electrode (GCE) to obtain a sensor for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). GO and TmPO4 were synthesized via the Hummers method and by a hydrothermal method, respectively. The nanocomposite was characterized by transmission electron microscopy, energy dispersive X-ray spectroscopy, powder X-ray diffraction and Fourier transform infrared spectroscopy. The electrochemical properties of the modified GCE were studied by electrochemical impedance spectroscopy and cyclic voltammetry. The good performance of the modified GCE results from the synergistic effects between GO with its good electrical conductivity and of TmPO4 as the electron mediator that accelerates the electron transfer rate. Compared to a bare GCE, a GO/GCE and a TmPO4/GCE, the GO/TmPO4/GCE exhibits three well-defined and separated oxidation peaks (at -0.05, +0.13 and+0.26V vs. SCE). Responses to AA, DA and UA are linear in the 0.1-1.0mM, 2-20M and 10-100M concentration ranges, respectively.