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International Journal of Electrochemistry
Volume 2011 (2011), Article ID 185864, 7 pages
http://dx.doi.org/10.4061/2011/185864
Research Article

Electroanalytical Characterisation of Dopa Decarboxylase Inhibitors Carbidopa and Benserazide on Multiwalled Carbon Nanotube and Poly(Nile blue A) Modified Glassy Carbon Electrodes

1Departamento de Química, Faculdade de Ciências e Tecnologia Universidade de Coimbra, 3004-535 Coimbra, Portugal
2Faculty of Pharmacy, Karadeniz Technical University, 61080 Trabzon, Turkey

Received 1 March 2011; Accepted 22 March 2011

Academic Editor: Bengi Uslu

Copyright © 2011 Dilek Kul and Christopher M. A. Brett. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Modified glassy carbon electrodes have been made by deposition of functionalised multiwalled carbon nanotubes (MWCNTs) followed by formation of poly(Nile blue) (PNB) films by electropolymerisation, using potential cycling in 0.1 M phosphate buffer solution (PBS) at pH 6.0. The electrochemical oxidation of carbidopa (CD) and benserazide (BS) on these MWCNTs/PNB-modified electrodes was investigated using cyclic and differential pulse voltammetry in 0.1 M PBS at different values of pH between 5.0 and 8.0; both CD and BS gave one diffusion-controlled irreversible oxidation peak in cyclic voltammetry. Analytical characterisation of CD and BS was carried out in 0.1 M PBS, pH 5.0. Peak currents in differential pulse voltammetry were linear over the concentration range of 1×105 to 1×104 M for CD and 4×106 to 4×105 M for BS. The repeatability, precision, and accuracy of the method were also investigated. Higher sensitivities and lower detection limits, of 1.17 μM for CD and 0.50 μM for BS, were obtained with this new modified electrode compared with previous studies reported in the literature.