Analysis with Microelectrodes Using Microsoft Excel Solver

The use of curve fitting for the analysis and interpretation of voltammetric data obtained while working with microelectrodes is discussed as a useful exercise for introducing students to the principle of problem solving using least-squares curve-fitting techniques. The advantages associated with this approach to data processing over the approach where the limiting current (i,L) alone is used are discussed and its limitations are highlighted.

This technique was applied to the determination of unknown concentrations of ferrocyanide and the most satisfactory recovery of concentrations was found when both the values of the formal potential (E 0¢ ) and concentration (C) were varied to match the experimental results with an equation characterizing the current potential curve for a reversible couple. In this case recoveries of 100% ± 5% were obtained for the concentration range 5 x 10-4 to 1 x 10-2 M. It was also found that Solver was unable to fit the equation when the sum of squared residuals was <2 x 10-9. This technique can be generalized for use with a number of other electrochemical experiments such as polarography, rotating disk electrochemistry, and normal pulse polarography.