Linear-scan anodic stripping voltammetry with thin-film electrodes: Theory of the stripping stage and experimental tests

The principles of thin-layer anodic stripping voltammetry, are discussed and a model for the stripping stage is developed for anodization by a linear potential ramp. The model assumes uniformity of the amalgam concentration, reversible electrode behavior, and planar diffusion of the stripped ions away from the anode. The entire shape of the stripping peak is then predicted from the model. Several stringent tests are developed to assess how well the model accords with experimental reality, One of these tests is analogous to the ''log plot'' of classical polarography. Another relates the peak current of the stripping voltammogram to its area. Experiments were carried out on amalgams of cadmium and lead formed by cathodic codeposition with the mercury onto an away of carbon microdisks in an unstirred solution, and the results have been used to test the model exhaustively. The results for lead amalgam agree well with the model, but agreement is less satisfactory for cadmium amalgam. A comparison is made of three rival methods of assaying the metal content of the amalgam.