Steady-State Voltammetry of Catechol and Guaiacol Analogues at Carbon Fiber Microdisk Electrodes Following Laser and Electrochemical Activation Procedures

Abstract

The steady-state voltammetric response (obtained at a scan rate of 100 mVas) for a series of catechol and guaiacol analogues at 11 mm carbon ®ber microdisk electrodes has been carefully characterized at fresh cut carbon ®ber surfaces and those activated by laser irradiation or by electrochemical pretreatment. The effectiveness of the two activation methods was assessed by comparing the half-wave potential, the electrochemical reversibility (waveslope analysis), the diffusion limited current, and the shape of the oxidative voltammetric wave(s) obtained following each activation procedure. Solution and activation conditions were systematically controlled with respect to buffer pH and composition as well as charge on the analyte. The data indicate that, in general, both electrochemical and laser activation procedures are equally effective at activating carbon ®ber microelectrodes for this set of compounds over a wide range of solution conditions, at least for voltammetry in the steady-state regime. The value of the half-wave potentials and the appearance of multiple voltammetric waves for some compounds has been rationalized based on the Hammett's s value (a measure of the electron-donating effect) of functional groups on the ring of the phenolic compounds studied. The additional voltammetric waves were observed only at high pH and occurred regardless of the activation procedure employed, indicating that the method of activation is not a determinant for occurrence of the ECE mechanism that apparently gives rise to voltammetric waves. Overall, laser and electrochemical activation result in very similar voltammetric behavior in the steady-state regime for the analytes studied.

Deviceless decoupled electrochemical detection of catecholamines in capillary electrophoresis using gold microband array electrodes

“…The potentials are shifted negatively by approx. 80 mV and 60 mV per pH unit when the pH is increased in the case of gold and catecholamines [28], respectively.…”

Influence of Geometry on the Electrochemical Response of Carbon Interdigitated Microelectrodes

“…4,5 In particular, microelectrodes have attracted attention for use in chemical analysis. [6][7][8][9][10][11][12][13] Both two-dimensional microdisk 6,9,10,13,14-16 and one-dimensional band 7,8,[17][18][19] electrodes are under investigation. An advantage of these microelectrode systems is the sensitivity to detection of low concentrations of electroactive species.Microelectrodes exhibit a different electrochemical response to redox species in solution than large planar electrodes.…”