Simultaneous determination of ascorbic acid, adrenaline and uric acid at a hematoxylin multi-wall carbon nanotube modified glassy carbon electrode

In this study, multi-wall carbon nanotubes (MWCNT) are evaluated as an immobilization matrix for the construction of a modified electrode based on hematoxylin electrodeposited on MWCNT immobilized on the surface of a glassy carbon electrode, GCE. The results show that the reversibility of hematoxylin is significantly improved at a MWCNT modified GCE in comparison with GCE alone. Hematoxylin MWCNT modified GCE (HMWCNT-GCE) shows an excellent electrocatalytic activity for adrenaline (AD) oxidation, with a diminution of the electrode overpotential of about 395 mV. The detection limit of 0.024 mu M and two linear calibration ranges of 0.2-78.3 mu M and 78.3-319.7 mu M are obtained for AD determination at HMWCNT-GCE surface using a differential pulse voltammetric method. This modified electrode is found quite effective not only in detection of ascorbic acid (AA), AD, and uric acid (UA), but also in simultaneous determination of each component in a mixture. HMWCNT-GCE has been applied to determination of AD in an adrenaline injection and of UA in a human urine sample with satisfactory results. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.