Automatic polarographic elucidation of electrode mechanisms by means of a knowledge-based system: Part 3: Mechanisms ECE, EE and mechanisms involving adsorption

The previously described expert system has been extended: rules allowing the elucidation of a larger number of mechanisms have been added and automatic control of additional experimental parameters such as concentration and composition of the solution in the cell and the electrode size has been made possible. The new rules cover a number of mechanisms consisting of two electron transfer steps (ECE, EE, 'square' and triangle'' schemes) and simple mechanisms in which either the reactant or the product undergoes a fast, reversible adsorption. Previously used criteria for the detection of a net reaction in the system and for the determination of the type of the electron transfer were made more robust by combining results obtained with cyclic voltammetry and convolution voltammetry. With the present set of rules, the expert system is capable to evaluate 39 mechanisms and their variants. To validate this set, the system was run with a number of compounds for which reaction mechanisms have already been studied. In all cases, the mechanism found as the most probable was the correct one. The time of the elucidation depended on the number of experiments that had to be done and varied from 4 up to 6 h. During this time, the system worked practically without human supervision.