Numerical determination of extended semi integrals and semi differentials by using spline cubic functions. Applications to an EE reversible mechanismin cyclic voltammetry

In this work, we propose a new general method based on the use of cubic spl ine functions, suitable for the numerical determination of extended semi in tegrals and semi differentials. The procedure combines these interpolation functions with different numerical integration and differentiation standard methods, including commercial software. The method has been applied to the electrochemical reduction of the meso-tetra(4-N-methylpyridyl)porphyrin in acidic aqueous solution, where this compound exhibits a two-electron wave in cyclic voltammetry. In this work, we determine the semi differential of the current and demonstrate that the signals obtained correspond to an EE p rocess, where both electrochemical steps are reversible and their formal po tentials are very close. (C) 2000 Elsevier Science S.A. All rights reserved .