Electrocatalytic Reduction of Nitrite by Phosphotungstic Heteropolyanion. Application for Its Simple and Selective Determination

Abstract

AbstractThree couples of reversible redox peaks of the PW12O403− (PW12) anion, which are composed of two one‐electron and one two‐electron processes occur in the potential range from +0.25 to −0.7 V in aqueous solutions. The electrocatalytic reduction of nitrite has been studied by the first redox couple of the PW12 anion at the surface of a carbon paste electrode. Cyclic voltammetric and chronoamperometric techniques were used to investigate the suitability of PW12 anion as a mediator for nitrite electrocatalytic reduction in aqueous solution with strongly acidic concentration of H2SO4. Results showed that H2SO4 1.00 M is the best medium for this purpose. In the optimum concentration of H2SO4, the electrocatalytic ability about 500 mV can be seen and the homogeneous second‐order rate constant (ks) for nitrite coupled catalytically to PW12 anion was calculated as 2.52×103 M−1 s−1 using the Nicholson–Shain method. According to our voltammetric experiments, the catalytic reduction peak current was linearly dependent on the nitrite concentration and the linearity range obtained was 3×10−5 to 1.00×10−3 M. The detection limit has been found to be 2.82×10−5 M (2σ). This method has been applied as a selective, simple, and precise method for determination of nitrite in real samples.