A Voltammetric Sensor Based on Chemically Reduced Graphene Oxide-Modified Screen-Printed Carbon Electrode for the Simultaneous Analysis of Uric Acid, Ascorbic Acid and Dopamine

A disposable screen-printed carbon electrode (SPCE) modified with chemically reduced graphene oxide (rGO) (rGO-SPCE) is described. The rGO-SPCE was characterized by UV-Vis and electrochemical impedance spectroscopy, and cyclic voltammetry. The electrode displays excellent electrocatalytic activity towards uric acid (UA), ascorbic acid (AA) and dopamine (DA). Three resolved voltammetric peaks (at 183 mV for UA, 273 mV for AA and 317 mV for DA, all vs. Ag/AgCl) were found. Differential pulse voltammetry was used to simultaneously detect UA, AA and DA in their ternary mixtures. The linear working range extends from 10 to 3000 M for UA; 0.1 to 2.5 M, and 5.0 to 2 x 10(4) mu M for AA; and 0.2 to 80.0 M and 120.0 to 500 mu M for DA, and the limits of detection (S/N = 3) are 0.1, 50.0, and 0.4 M, respectively. The performance of the sensor was evaluated by analysing spiked human urine samples, and the recoveries were found to be well over 98.0% for the three compounds. These results indicate that the rGO-SPCE represents a sensitive analytical sensing tool for simultaneous analysis of UA, AA and DA.