Assessment of the accuracy of estimating adsorption parameters of organic substances from differential capacitance curves: Monte-Carlo simulation of the random-error effect in capacitance measurements

Monte-Carlo method is used for elucidating the effect of a random normally distributed error of capacitance measurements on estimated adsorption param eters of organic substances on an ideally polarizable electrode. Within the model of two parallel capacitors and a Frumkin isotherm with preset adsorp tion parameters, initial differential capacitance vs. potential dependences are calculated for ten organic-substance concentrations. Then, a random no rmally distributed error is introduced at every point in these dependences. For estimating the adsorption parameters, 100 series of dependences thus o btained are processed by a nonlinear regression analysis technique. Histogr ams of distributions of found parameters are plotted. The accuracy of the p arameter calculation is assessed for 5 and 10% errors of capacitance measur ements.