Electroanalysis using differential pulse methods at a rotating disk electrode

Application of a differential pulse waveform to a rotating disk electrode ( RDE) results in a peaked response for amperometric redox reactions. Based o n this observation two models were proposed which describe the limiting cas es. Model 1 assumes that the current subsequent to the pulse dominates, whi le Model 2 assumes that the pulse width is sufficiently long to allow a ste ady-state current to exist during the pulse width. Simulations of the deriv ative of the equation describing the sigmoidal response were also carried o ut. Model 1 was found to be unsuitable for the system studied here (pulse w idth: 55 ms) and is more suited to systems where shorter pulse widths are u sed. The correlation between peak current heights returned by Model 2 and t hose recorded experimentally was poor but the theoretical results followed the same trends as those observed experimentally. This technique was found to have a limit of detection of 2.3 x 10(-5) M and a limit of quantitation of 7.68 x 10(-5) M for the [Fe(CN)(6)](4-) system.