Poly(ortho-toluidine) modified for electrocatalytic reduction carbon paste electrode:: A sensor of nitrite

The electrocatalytic reduction of nitrite has been studied by poly(ortho-toluidine) films modified carbon paste electrode (P-OT/MCPE). Cyclic voltammetry and chronoamperometry techniques were used to investigate the suitability of poly(ortho-toluidine) as a mediator for the clectrocatalytic nitrite reduction in aqueous solution with various pH. Results showed that pH 0.00 is the most suitable for this purpose. In the optimum pH, the reduction of nitrite occurs at a potential about 600 mV more positive than unmodified carbon paste electrode. The catalytic reaction rate constant, (k(n)), was calculated 8.68 x 10(2) W s(-1) by the data of chronoamperometry. The catalytic reduction peak current was linearly dependent on the nitrite concentration and the linearity range obtained was 5.00 x 10(-4) M - 1.90 x 10(-2) M. Detection limit has been found to be 3.38 X 10(-4) M (2 sigma). This method has been successfully employed for quantification of nitrite in real sample.