Potentialstep-Chronoamperometry as a Method for Determining Diffusion Coefficients of High Trueness and of High Precision

A chronoamperometric method for obtaining experimental values of diffusion coefficients with high trueness and precision was described. In this method, the chronoamperograms were analyzed by using the most precise theoretical equation available. All of the variables that appear in the equation had been absolutely determined with instruments calibrated traceably. Experiments were carried out so conscientiously that the demands of the theoretical equation would be realized as well as possible. The obtained chronoamperogram was fitted to the theoretical equation by two adjustable parameters : the diffusion coefficient and the concentration of the diffusing spices. Each chronoamperogram was inspected concerning how it fitted the theoretical equation over the observed time range and how the obtained concentration agreed with the actually known one. By this inspection the trueness of the value of the diffusion coefficient was assessed. For an example of showing the importance of the trueness of the experimental values, the diffusion coefficients of fullerene in references were shown along with the values obtained by this method.