Electrocatalytic oxidation and determination of nitrite on carbon paste electrode modified with oxovanadium(IV)-4-methyl salophen

Electrocatalytic oxidation and detection of nitrite at a carbon paste electrode chemically modified with N,N'-bis(salicylaldehyde)-4-methyl-1,2-phenylenediimino oxovanadium(IV) as a Schiff base complex ([VO(SB)]), was thoroughly investigated. Anodic oxidation of nitrite (in pH 4) at the [VO(S B)]-modified carbon paste electrode occurred at low overpotential (0.87 V versus Ag/AgCl), and treatment of the voltammetric data showed that it was a purely diffusion-controlled reaction involving one-electron in the rate-determining step. The mechanism for the interaction of nitrite with the vanadium(IV) Schiff base complex is proposed to involve the V-IV(SB)(2+)/V-III(SB)(+) redox process. The modified electrode exhibits good catalytic activity for the oxidation of nitrite with good sensitivity over the wide concentration range of 3.90 x 10(-6)-4.05 x 10(-3) M nitrite, and a detection limit of 6.13 x 10(-7) M (S/N = 3). The heterogeneous rate constant, k(1), and the standard heterogeneous rate constant, k(0), for the oxidation of nitrite at the surface of the modified electrode were determined by rotating disk electrode voltammetry using the Koutecky-Levich plot. The transfer coefficient (alpha) for electrocatalytic oxidation of nitrite and the diffusion coefficient of this substance under the experimental conditions were also investigated in this study. (c) 2007 Elsevier B.V. All rights reserved.