The electrocatalytic oxidation of L-Cysteine (L-Cys) has been studied by Indigo carmine (IND) at the glassy carbon electrode (GCE). Cyclic voltammetry and chronoamperometry techniques were used to investigate the suitability of IND as a mediator in aqueous solution with various pHs. It has been found that under the optimum conditions (pH 8.0) the oxidation of L-Cys occurs at a potential of about 290 mV less positive than that of an unmodified GCE. The heterogeneous electron transfer rate constant between IND and the GCE and the diffusion coefficient of IND were estimated to be about 2.62×10-3 cm s-1 and 4.10×10-6 cm2 s-1, respectively. The diffusion coefficient of L-Cys (D= 1.8×10-6 cm2 s-1), and its kinetic parameters such as electron transfer coefficient, (α = 0.41) and the catalytic reaction rate constant, (k=5.9×104 M-1s-1) were also determined using electrochemical approaches. The voltammetric response of the modified electrode was linear against the concentration of L-Cys in the ranges of 1.0×10-4 M- 1.5×10-2 M with cyclic voltammetry method. The detection limit (3σ) was determined as 5.1×10-5.
کلید واژگان :L-cysteine; glassy carbon electrode; electrocatalysis; indigo carmine
ارزش ریالی : 600000 ریال
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