One-dimensional NiFe2O4 nanorods modified with sulfur-rich spherical carbon nanoparticles for simultaneous voltammetric determination of ascorbic acid, dopamine and uric acid

The work reports an easy way to prepare sulfur doped-carbon nanoparticles on a NiFe2O4 support. By placing the nanocomposite on a glassy carbon electrode (GCE), a sensor is obtained for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The morphology, structural and chemical composition of the nanocomposite was characterized by various surface and physicochemical techniques, and its electrochemical properties were also examined. Modified GCE showed resolved electrocatalytic oxidation activity of AA, DA and UA with well separated peaks at 242mV, 111mV and 353mV (vs. SCE). Under optimized conditions, the sensor has wide linear ranges and detection limits as low as 45, 25 and 17nM for AA, DA and UA, respectively. The outstanding electrocatalytic performance of this GCE is attributed to the synergistic effect, defined size and unique morphology of the nanocomposite. This provides a benign micro-environment for convenient conjugation of biomolecules and improved charge transfer between the electrode and biomolecules for effective oxidation. The sensor was applied to the determination of AA in commercial vitamin C tablets, DA in injections, and UA in human urine. It showed recoveries in the range of 99.7-102.2%.