Electroanalysis Using Differential Pulse Methods and Stripping Techniques.

Application of a differential pulse waveform to a microelectrode or a rotating disk electrode results in a peaked response for amperometric redox reactions. Based on these observations models were proposed and tested for these methods. Simulations of the models were carried out by inputting the relevant equations into Microsoft Excel. The microelectrode study revealed a good correlation between one model and the numerical derivative of the current following a linear sweep potential waveform. Experimentally the derivative can be obtained numerically following a linear sweep. The alternative differential pulse waveform requires more sophisticated equipment and the response can be affected by slow kinetics. The limit of detection for the rotating disk electrode system was 2.3x10-5M with a limit of quantitation of 7.68x10-5M for the [Fe(CN)6]4 system. The use of curve fitting for the analysis and interpretation of voltammetric data obtained while working with microelectrodes was investigated. Microsoft Excel Solver was the curve fitting package used for this study. 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 (E0) and concentration © were varied to match the experimental results with an equation characterising the current potential curve for a reversible couple. In this case recoveries of 100%+/-5% were obtained for the concentration range 5x10-4 M to 1x10-2M. It was also found that Solver was unable to fit the equation when the sum of squared residuals wa