Voltammetric measurement of trace amount of glutathione using multiwall carbon nanotubes as a sensor and chlorpromazine as a mediator

Journal of Solid State Electrochemistry (Impact Factor: 2.23). 08/2010; 14(8):1415-1423. DOI: 10.1007/s10008-009-0978-z

ABSTRACT In this work, we propose chlorpromazine as a new mediator for the rapid, sensitive, and highly selective voltammetric determination
of glutathione (GSH) using multiwall carbon nanotubes paste electrode (MWCNTPE). The experimental results showed that the
carbon nanotubes paste electrode has a highly electrocatalytic activity for the oxidation of GSH in the presence of chlorpromazine
as a mediator. Cyclic voltammetry, double potential step chronoamperometry, and differential pulse voltammetry (DPV) are used
to investigate the suitability of chlorpromazine at the surface of MWCNTPE as a mediator for the electrocatalytic oxidation
of GSH in aqueous solutions. It is shown that chlorpromazine can catalyze the oxidation of GSH in an aqueous buffer solution
to produce a sharp oxidation peak current at about +0.70 versus Ag/AgCl as a reference electrode. Kinetic parameters such
as electron transfer coefficient and catalytic reaction rate constant, k/h, are also determined. Using DPV and under the optimum
conditions at pH 4.0, the electrocatalytic oxidation peak current of GSH shows a linear dependence on GSH concentration in
the GSH concentration range of 0.3 to 18.3µM. The detection limit (3σ) is determined to be 0.16µM. The relative standard deviation for 1.5 and 5.0µM GSH are found to be 3.7% and 2.5%, respectively.
The proposed method may, thus, also be used as a novel, selective, simple, and precise method for the voltammetric determination
of GSH in such real samples as hemolyzed erythrocyte.

KeywordsChlorpromazine-Electrocatalysis-Glutathione determination-Voltammetric methods

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