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Steady‐State Voltammetry of Catechol and Guaiacol Analogues at Carbon Fiber Microdisk Electrodes Following Laser and Electrochemical Activation Procedures
Author(s) -
Strein Timothy G.,
Ximba Bhekemusa J.,
Hamad Alyssandrea H.
Publication year - 1999
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/(sici)1521-4109(199901)11:1<37::aid-elan37>3.0.co;2-4
Subject(s) - cyclic voltammetry , electrochemistry , catechol , chemistry , analytical chemistry (journal) , voltammetry , electrode , horizontal scan rate , glassy carbon , guaiacol , inorganic chemistry , chromatography , organic chemistry , catalysis
The steady‐state voltammetric response (obtained at a scan rate of 100 mV/s) for a series of catechol and guaiacol analogues at 11 µm carbon fiber microdisk electrodes has been carefully characterized at fresh cut carbon fiber 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 fiber 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 σ 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.