Sensitive Electrochemical Sensor for Simultaneous Determination of Dopamine, Ascorbic Acid, and Uric Acid Enhanced by Amino-group Functionalized Mesoporous Fe3O4@Graphene Sheets

The electrochemical sensor based on amino-group functionalized mesoporous Fe3O4 (Fe3O4-NH2)@graphene sheets (GS) was constructed to simultaneously determine small biomolecules such as ascorbic acid (AA), dopamine (DA) and uric acid (UA). Due to the synergetic effect between GS and Fe3O4-NH2, the modified glassy carbon electrode not only improved the electrochemical catalytic oxidation of AA, DA, and UA, but also resolved the overlapping anodic peaks. Several important parameters controlling the performance of the electrochemical sensor were investigated and optimized. Using the modified electrode with differential pulse voltammetry (DPV) method, the linear response ranges for the determination of AA, DA, and UA were 5.0-1600 μmol L−1, 0.2-38 μmol L−1, and 1.0-850 μmol L−1 in the co-existence systems of these three species under optimum condition, respectively. The detection limits (S/N = 3) were found to be 0.074 μmol L−1, 0.126 μmol L−1, and 0.056 μmol L−1 for the determination of AA, DA, and UA, respectively. Satisfactory results were achieved for the determination of DA, AA, and UA in DA hydrochloride injection, vitamin C injection, and human urine samples, respectively. The results imply that the electrochemical sensor has the advantages of simplicity, high sensitivity and good selectivity.