Zeroth-order solution and higher-order corrections for the CE mechanism in double potential step techniques

Abstract

The general solution for all modes of double-pulse voltammetry for an electrode process under Nernstian behaviour coupled with a prior fast first order chemical reaction (CE mechanism) has been derived. This allows us to describe the characteristics of differential pulse polarography (DPP), differential normal pulse polarography (DNPP), reverse pulse polarography (RPP), and double potential step chronoamperometric responses, among others. Also, quantitative kinetic data analysis that allows us to determine the rate constants of the chemical reaction from these responses is discussed. It is worth emphasizing that the DNPP and chronoamperometric responses can be examined since the solution obtained is not limited by the restriction t′/ t ≪ 1 (where t′ is the duration of the second step), and this is due to the fact that the current response as t′ increases can be computed to any degree of accuracy by including as many higher-order corrections as necessary. A comparative study with the predictions of the solution previously reported by Kim and Birke (Anal. Chem., 55 (1983) 1735) for the DPP response involved with this mechanism is presented.