Comparison of electrochemical property between multiwalled carbon nanotubes and porous graphitized carbon monolith modified glassy carbon electrode for the simultaneous determination of ascorbic acid and uric acid

In this work, glassy carbon electrode (GCE) was modified with porous graphitized carbon monolith (CM) as a new nanomaterials and multi-walled carbon nanotubes (MWCNTs) for simultaneous determination of ascorbic acid (AA) and uric acid (UA). Scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were employed for the surface analysis of the modified electrodes. In this simultaneous detection, the electrochemical response of AA and UA on MWCNTs/GCE exhibited broad anodic peaks and were resolved into separated CV peaks at +45 mV and +254 mV, respectively. In comparison, two well resolved peaks of CM/GCE were obtained at -39 mV and +233 mV with flat base-lines for oxidation of AA and UA, respectively. Under the optimum conditions, the performance of porous graphitized carbon monolith were superior to MWCNTs modified glassy carbon electrode. For CM/GCE, the oxidation peak current was linearly dependent on AA and UA concentration in the range 0.195-4.04 mM and 0.094-1.90 mM, with the correlation coefficients (R-2) greater than 0.997. Detection limits (S/N= 3) were found 0.39 u,M and 0.15 mu M for AA and UA, respectively. The recoveries of the AA and UA from spiked human serum were 76.0-94.2%. In addition, the CM/GCE showed high sensitivity, good reproducibility and long-time stability at least 1 month without significant loss of electrochemical signal. (C) 2014 Elsevier B.V. All rights reserved.