A Carbon-Black-Doped Molybdenite-Based Electrochemical Sensor for Simultaneous Determination of Uric Acid, Dopamine, and Ascorbic Acid

A simple, rapid, cost-effective and non-enzymatic amperometric sensor for sensitive and simultaneous determination of uric acid (UA), dopamine (DA), and ascorbic acid (AA) was developed based on a new combination of carbon black (CB) and molybdenite (MLN) modified glassy carbon electrode (GCE). The synergistic effect of CB and MLN can increase electrode's conductivity, accelerate the electrochemical catalytic reaction and enhance the oxidation currents of UA, DA and AA. Cyclic voltammetry demonstrated the sensor to perform excellently in the electrochemical oxidation of AA, DA and UA, respectively. The oxidation potentials are well separated (oxidation peaks at -50 mV, 200 mV and 350 mV vs. Ag/AgCl) for AA, DA and UA with the detection limits of 5 mu mol/L, 8.7 mu mol/L and 9 mu mol/L (S/N=3), respectively. The MLN-CB/GCE sensor also demonstrated superior electrochemical properties including good stability, selectivity and reproducibility. In addition, the prepared sensor for UA allowed the determination of UA in highly diluted body fluids (urine), and the analytical results obtained by the present sensor were in good agreement with those obtained by conventional spectrophotometry.