Abstract
There is a difference between the electrolysis potential of mercury (II) -DTPA complex and that in adding a metal ion to the complex. This difference depends on the stability constant of the complex made of the metal ion and DTPA. So it would be possible to determine some metal ions, if a suitable potential has been fixed. This report deals with a controlled potential coulometric method for determining copper and zinc ions which form stable complexes with DTPA, and calcium ion which forms a less stable complex. Mercury-coated platinum was used as the working electrode. In 0.1M ammonia-ammonium nitrate electrolyte (pH=10) and at-0.05V vs. SCE, these ions in about 1 mg of the samples were determined with good accuracies.
