Synthesis and Characterization of Magnetic Fe3O4/Reduced Graphene Oxide and its Application in Determination of Dopamine

An electrochemical sensor to determine dopamine in the human body was fabricated based on modified iron oxide/reduced graphene oxide/glassy carbon electrode (Fe3O4/r-GO/GCE). Determination of dopamine is significance nowadays as the abnormal level may cause various mental health diseases as well as Parkinson’s disease. The Fe3O4/r-GO nanocomposite was synthesized via Hummer’s method with a slight modification and characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Brunauer Emmett-Teller (BET). The presence of Fe3O4 onto the surface of r-GO was confirmed by SEM analysis which shows the bulky porous sponge-like structure attached to an exfoliated sheet of r-GO. FTIR analysis proved the presence of the functional group in existing composites via oxidation process of graphene oxide and reduction process of reduced graphene oxide while the crystalline form of Fe3O4/r-GO was determined using XRD analysis. The diffraction peaks index to the cubic phase was noticeable indicating the successful crystallization of the composites. The catalytic activity of bare GCE and modified GCE (Fe3O4/r-GO/ GCE) were observed using electrochemical characterization of cyclic voltammetry, differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) with optimum pH of 7, a concentration of 100 μM, and the scan rate of 250 mV s-1. The observed DPV response linearly depends on dopamine concentration in the range of 20-100 μM, with correlation coefficients of 0.9876. The detection limit obtained for the real sample analysis was found to be 0.569 μM while the limit of quantitation was 1.897 μM. The percentage of recovery, repeatability and reproducibility was 113, 82.81 and 7.19 %, respectively.