Simultaneous voltammetric determination of dopamine and uric acid using carbon-encapsulated hollow Fe3O4 nanoparticles anchored to an electrode modified with nanosheets of reduced graphene oxide

The authors describe an electrochemical sensor for simultaneous determination of dopamine (DA) and uric acid (UA). The sensor is based on the use of composite materials of carbon-encapsulated hollow magnetite (Fe3O4) nanoparticles and graphene oxide nanosheets, which were homogeneously deposited on a glassy carbon electrode. The morphology of the materials was characterized by transmission electron microscopy and scanning electron microscopy, and the properties of differently decorated electrodes were investigated via cyclic voltammetry and differential pulse voltammetry (DPV). Simultaneous detection of DA and UA was carried out via DPV, and the potentials of electrooxidation peaks are 0.14 V and 0.27 V (vs. SCE) for DA and UA, respectively. The calibration plot is linear from 0.1 to 150 μM for DA, and from 1.0 to 100 μM for UA, with detection limits of 0.053 μM and 0.41 μM at an S/N ratio of 3. The method was applied to the quantification of DA and UA in brain tissue, urine and whole blood.