Examination of staircase, normal pulse and differential pulse voltammetry at inlaid ultramicroelectrodes using a computerized multi-time-domain measure

Abstract

A microprocessor-based electrochemistry system with the capability of measuring peak height, width at half peak height and peak potential as a function of time, has been used to assess the techniques of multi-time-domain staircase, pseudo-derivative staircase, normal pulse, pseudo-derivative normal pulse and differential pulse voltammetry at disk, line, ring and array ultramicroelectrodes. Linear diffusion contributions to the ultramicroelectrode response are slightly greater with pulse than with staircase methods. However, the staircase, pulse and differential pulse techniques at ultramicroelectrodes are more noted for their similarities than differences, unlike the case at the conventional-size electrodes where current magnitude and even shapes are very technique dependent. The similarity arises because spherical or cylindrical rather than planar diffusion terms are dominant even when employing time domains down to 1 ms. Since the multi-time pseudo-derivative staircase method is inherently simpler than the pulse methods, as well as being analytically equivalent to the pulse methods with respect to sensitivity, this technique is useful for characterizing electrode processes rapidly, recognizing imperfections in ultramicro-electrode fabrication and detecting instrumental limitations associated with short-time-domain measurements with or without potentiostatic control.