Which of three voltammetric methods, when applied to a reversible electrode reaction, can best cope with double-layer capacitance and severe uncompensated resistance?

The presence of uncompensated resistance and double-layer capacitance confo unds the accurate measurements of the bulk concentration of electroreactant and the reversible half-wave potential from an experimental voltammogram, It is pertinent to ask which simple voltammetric technique-chronopotentiome try, linear-scan voltammetry, or potential-step voltammetry-is best able to confront these difficulties. We have carried out a modeling study in an at tempt to answer this question, First, we devised an exact method of simulat ing each variety of reversible voltammogram, incorporating the effects of r esistance and capacitance. Next, we developed an unprejudiced method of ana lyzing these voltammograms to recover both electrochemical parameters. Then we performed a sensitivity analysis on a very large number of simulated vo ltammograms by measuring the apparent half-wave potential and concentration when slightly erroneous values of resistance and capacitance were employed in the recovery step. Thereby we hoped to ascertain how uncertainty in the magnitudes of the two interfering electrical elements affects the measured values of the two electrochemical parameters. Basing conclusions on the si zes of the four sensitivity indices, we conclude, surprisingly, that linear -scan voltammetry, not chronopotentiometry, is most often the method of cho ice.