Electrochemical Oxidation of Cytosine on Carbon Paste Electrode and Its Determination

In this paper electrochemical oxidation of cytosine was investigated on a carbon paste electrode for the first time. In pH 5.0 Britton-Robinson (B-R) buffer solution a well-define irreversible oxidation peak appeared at the potential of 1.480 V (vs. SCE), which indicated the electrooxidation of cytosine on the electrode. The electrochemical behaviors of cytosine were carefully investigated by cyclic voltammetry at the selected conditions. The electrochemical parameters such as electron transfer number (n), electron transfer coefficient (alpha) and electrode reaction standard rate constant (k(s)) was calculated with the results as 2.14, 0.15 and 1.049 x 10(-3) s(-1), respectively. Under the optimal conditions a good linear relationship was constructed between the cytosine concentration and the differential pulse voltammetric current in the range from 10.0 to 1000.0 mu mol/L with the linear regression equation as Ip(mu A) = 0.0519C (mu mol/L) + 0.419 (gamma = 0.999) and the detection limit as 1.9 mu mol/L (3 sigma).