Electrocatalytic oxidation and voltammetric determination of L-cysteic acid at the surface of p-bromanil modified carbon paste electrode

The electrochemical properties of L-cysteic acid studied at the surface of p-bromanil (tetrabromo-p-benzoquinone) modified carbon paste electrode (BMCPE) in aqueous media by cyclic voltammetry (CV) and double step potential chronoamperometry. It has been found that under optimum condition (pH 7.00) in cyclic voltammetry, the oxidation of L-cysteic acid at the surface of BMCPE occurs at a half-wave potential of p-bromanil redox system (e.g., 100 mV vs. Ag vertical bar AgCl vertical bar KClsat), whereas, L-cysteic acid was electroinactive in the testing potential ranges at the surface of bare carbon paste electrode. The apparent diffusion coefficient of spiked p-bromanil in paraffin oil was also determined by using the Cottrell equation. The electrocatalytic oxidation peak current Of L-cysteic acid exhibits a linear dependency to its concentration in the ranges of 8.00 x 10(-6) M-6.00 x 10(-3) M and 5.2 x 10(-7) M - 1.0 x 10(-5) M using CV and differential pulse voltammetry (DPV) methods, respectively. The detection limits (2a) were determined as 5.00 x 10(-6) M and 4.00 x 10(-7) M by CV and DPV methods. This method was used as a new, selective, rapid, simple, precise and suitable voltammetric method for determination of L-cysteic acid in serum of patient's blood with migraine disease.