Electroanalytical Methods of Analysis: Polarography and Voltammetry

Authored by: A. David Woolfson

Encyclopedia of Pharmaceutical Science and Technology

Print publication date:  July  2013
Online publication date:  July  2013

Print ISBN: 9781841848198
eBook ISBN: 9781351124874
Adobe ISBN:

10.1081/E-EPT4-v2-40

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Abstract

Voltammetry is a term that encompasses all measurements based on controlled electrolysis at a microelectrode. Polar-ography, first introduced by the Czech electrochemist Jaroslav Heyrovsky in 1922, is voltammetry at a special form of mercury microelectrode, the dropping mercury electrode (DME). Mercury electrodes can only be driven to negative potentials because otherwise, the metal dissolves in aqueous solutions as Hg2+. Consequently, polarography is an electroanalytical method based on the cathodic reduction of electroactive species, either metal cations or electroreducible organic species, in an electrically conducting solution. By contrast, voltammetry is based on electroanalysis involving anodic oxidation, preferably in a flowing system in which a self-cleaning action prevents fouling of the solid electrode surface by the products of the electrochemical reaction, thereby leading to nonreproducible current/voltage curves.

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