Comparison of electrochemical oxidation of epinephrine in the presence of interfering ascorbic and uric acids on gold electrodes modified with S-functionalized compounds and gold nanoparticles

Mercaptopropionic acid (MPA), gold nanoparticles (Au-NPs) and cystamine (CA) modified gold bare electrodes have been applied in voltammetric sensors for simultaneous detection of epinephrine (EP), ascorbic (AA) and uric (UA) acids. Modification of the electrode surface by self-assembled layers (SAMs) improves the reactivity of a gold electrode for EP oxidation remarkably. A linear relationship between the epinephrine concentration and the current response is obtained in the range of 0.1-700 mu M with the detection limit >= 0.042 mu M for the electrodes modified at 2D template and in the range of 0.1-800 mu M with the detection limit >= 0.040 mu M for the electrodes modified at 3D template. The results have shown that the overlapping voltammetric response of epinephrine, ascorbic and uric acids is well resolved at modified electrodes. The modified SAMs electrodes show high selectivity, sensitivity, reproducibility and stability. (C) 2009 Elsevier Ltd. All rights reserved.