The Potentiometric Effect of As(III) Ion on a Belousov-Zhabotinskii Oscillating Chemical Reaction. Application to the Determination of As(III)

A novel analytical method that builds on specific features of non-linear chemical systems far from thermodynamic equilibrium is described. The used oscillating chemical system is the BZ (Belousove-Zhabotinskii) reaction in a non-equilibrium stationary state close to a bifurcation point. The method uses a Pt electrode for monitoring the potential response to a perturbation caused by As(III) ion. A linear response, in which the oscillating amplitude varies versus the logarithm of the As (III) concentration, was found in the range of 1.99 × 10^-6-1.27 × 10^-4 M. Under optimum conditions, a detection limit of 2 × 10^-6 M for As(III) was obtained. The relative standard deviation (%RSD) for As(III) 1.59 × 10^-5 M is 7.1 (n = 6).