Über fokussierenden Ionenaustausch VII. Quantitative Mikroanalyse von Schwermetallen und seltenen Erden
✍ Scribed by Ernst Schumacher; Hans Jakob Streiff
- Publisher
- John Wiley and Sons
- Year
- 1958
- Tongue
- German
- Weight
- 749 KB
- Volume
- 41
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Abstract
Focusing ion exchange as a method of separation of metal‐ions, taking place in homogeneous solution in the presence of a complex‐formation‐ and an electrical potential‐gradient, is again confronted with heterogeneous ion‐exchange and ionophoresis and the distinctions are stressed.
The phenomenon of “double‐focusing”, meaning the stationary existence of two lines of the same metal in the presence of two complexing agents (one of which is an amino‐poly‐acetic acid), offers a possibility for the estimation of μg‐ and ng‐amounts of various metals, incl. Fe^3+^, Cu^2+^, Pb^2+^, Co^2+^, Y^3+^, and heavy rare earths. This can not be realized with ordinary ion‐exchange nor electrophoresis.
One of the lines of a double‐focus, being located on the acid side of a pH‐gradient, changes its intensity proportionally to the added amount of a chelating agent (NTA, EDTA, Chel CD). Macro‐chelatometry, using external indicators, direct and substitution titrations of metal‐traces on a filter‐paper strip, are described. The method is more accurate than various micro‐chemical procedures.
A phenomenological treatment of double‐focusing is given.