Simultaneous determination of ascorbic acid, dopamine, uric acid and folic acid based on activated graphene/MWCNT nanocomposite loaded Au nanoclusters

An electrochemical sensor for the simultaneous determination of ascorbic acid (AA), dopamine (DA), uric acid (UA) and folic acid (FA) using gold nanoclusters (AuNCs)/activated graphene (AGR)/MWCNT nanocomposite was fabricated. The AGR/MWCNT nanocomposite was prepared via the electrochemical reduction of GR/MWCNT while AuNCs were formed onto the AGR/MWCNT film through the electrodeposition of Au. The AuNCs/AGR/MWCNT nanocomposite was characterized using different techniques, such as scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). The nanocomposite sensor exhibited sharp and obvious peaks for the oxidation of AA, DA, UA and FA as compared to a bare electrode. The AuNCs/AGR/MWCNT probe displays an efficient electron mediating behavior with well separated oxidation peak potentials between AA to DA, DA to UA and UA to FA were 0.21, 0.14 and 0.28V, respectively. The linear calibration curves of AA, DA, UA and FA were observed from 10-150 mu M, 1.0-210 mu M, 5.0-100 mu M and 10-170 mu M with detection limits of 0.27 +/- 0.1 mu M, 0.08 +/- 0.02 mu M, 0.10 +/- 0.03 mu M and 0.09 0.01 mu M, respectively. In addition, the analytical application of the proposed sensor was successfully conducted for the determination of these species in human urine real samples. (C) 2015 Elsevier B.V. All rights reserved.