Study of slightly soluble metal chelates by anodic stripping voltammetry

Abstract

Anodic stripping voltammetry has been used to study the chelates of ammonium 1-pyrrolidinecarbodithioate with metal ions. A technique is described in which polarographic waves are obtained when the chelates are highly insoluble. The metal is deposited at a hanging mercury drop electrode in the absence of chelating agent. The chelating agent is then added to the solution and the anodic stripping peak is recorded. Metal-to-ligand ratios and dissociation constants are calculated from the shift in the anodic stripping peak compared with the stripping peak obtained in the absence of chelating agent. Advantages include the ability to use polarographic techniques when the chelates are insoluble (and non-reducible), increased sensitivity, and the possibility of using concentrations rather than activities for calculations involving dilute solutions.