engleski

Study of Bismuth film Formation on Different Carbon Based Electrodes for Possible Applicability in Electroanalytical Determination of Cysteine

The Bi-film formation from acid nitrate solution on glassy carbon electrode (GCE), graphite electrode (GPE) and on an assembly of carbon fiber microelectrodes (CFME) were studied utilizing cyclic voltammetry (CV) and chronoamperometry (CA). Voltamemetric data obtained with all three electrodes indicate that bismuth electrodeposition is controlled by diffusion of Bi3+. In the case of GCE and GPE Bi3+ diffusion coefficient was calculated using Randles-Sevcik equation. Analysis of the experimental current transients, obtained with GCE and GPE, revealed that increment of Bi3+ concentration changes nucleation mechanism from three-dimensional (3D) progressive nucleation toward instantaneous. Transients obtained with CFME, at different Bi3+ concentrations, suggesting only 3D instantaneous nucleation mechanism. Obtained data were used for preparation of appropriate Bi layer on CFME (Bi-film/CFME) for electroanalytical determination of cysteine by using square wave cathodic stripping voltammetry (SWCSV). Optimization of the SWCSV parameters have resulted in good linearity over examined concentration range of 1.0 μmol dm-3 to 10.0 μmol dm-3, with detection limit of 0.028 μmol dm-3 and sensitivity of 398 nA µmol-1 dm3.

bismuth film; nucleation; carbon electrodes; stripping voltammetry; cysteine

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