Graphene–MultiwalledCarbon Nanotubes ModifiedGlassy Carbon Electrodes for Simultaneous Detection of Ascorbic Acid,Dopamine, and Uric Acid

This study compares the sensing performance of glassy carbon electrodes (GCE) modified with graphene (GR), multiwalled carbon nanotubes (MWCNTs), and graphene–multiwalled carbon nanotube (GR-MWCNT) composites for the simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA). Among these electrodes, GR-MWCNT/GCE exhibited the highest sensitivity and the lowest detection limit. Using differential pulse voltammetry (DPV), AA, DA, and UA can be simultaneously detected at low potentials of −0.032, 0.206, and 0.34 V vs Ag/AgCl, with sensitivities of 0.076, 1.38, and 0.181 μA μM^–1 and detection limits (LOD) of 6.71, 0.58, and 7.30 μM, respectively. The GR-MWCNT/GCE also demonstrated good stability, reproducibility, and excellent anti-interference capability. This newly fabricated sensor was confirmed to be applicable for the simultaneous detection of AA, DA, and UA in real serum and urine samples.