Renewable silver amalgam film electrodes in electrochemical stripping analysis-a review

The success of a voltammetric sensing procedure depends mainly on the proper choice of the working electrode. This is because its ability to accumulate the analyte determines the sensitivity of the method. The main criterion of the selection of the proper working electrode is the available potential window. A variety of conductive materials have been used for the preparation of working electrodes. Of these, two kinds of mercury electrodes-hanging mercury drop and film-were used because of their excellent voltammetric performance and, in particular, their high overpotential of hydrogen reduction. The significant drawbacks of mercury electrodes, however, are the toxicity of the material and the instability of liquid mercury films. To overcome these disadvantages, less toxic mercury-containing materials have been used, such as amalgams and amalgam film electrodes. This group includes renewable silver amalgam film electrodes used for electrochemical stripping sensing purposes. These electrodes have successfully been applied for anodic, adsorptive, cathodic, catalytic voltammetric, and potentiometric stripping determination of trace amounts of inorganic cations and organic compounds in various natural matrices. In this review, the electrode design, characteristics, and application of two kinds of renewable silver amalgam film electrodes are discussed in detail.