Capillary electrophoresis with chemical reaction Effect of ionic strength

Abstract

A brief summary of the results of experimental observations of the effects of electric fields on propagating reaction fronts and pulses is presented. A prototype ionic chemical system consisting of a substrate A⁺ and an autocatalyst B⁺ and two further non-reacting species C^- and D⁺ is then considered when an electric field with a constant current is applied. An autocatalytic reaction between A⁺ and B⁺ with a quadratic rate law is assumed. Results obtained from extensive numerical simulations of the model are reported. These show that the system is capable of supporting a variety of propagating fronts; ‘kinetic waves’, ‘Kohlrausch boundaries’ and complete species separation are all observed as well as a new type of wave front in which there is a much enhanced reaction rate. The behaviour is characterized in terms of the applied electric current, the ionic strength, and the ratio of the diffusion coefficients of the reacting species.