Complex-forming equilibria in isotachophoresis : IV. Simulation of isotachophoretic equilibria of metal ions forming multi-coordinated complexes

doi:10.1016/S0021-9673(00)91565-6

Journal of Chromatography A

Volume 280, 1983, Pages 219-231

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Abstract

A computational procedure is given for the qualitative analysis of isotachophoretic equilibria of metal ions forming labile multi-coordinated complexes with counter ions. For the zinc-α-hydroxyisobutyrate system, the qualitative index R_E of Zn²⁺ was simulated at pH  4.4 by varying the coordination numbers (1–3) and the stability constants of the complexes and the concentration of the leading ion, CtL. Different dependences of the R_E values on (fx219-2)CtL were obtained for the differently coordinated complexes, suggesting that the coordination numbers and the stability constants of complexes can be evaluated from the observed R_E values by the least squares method. The present method is applicable to the analysis of mixed complexes with different coordination numbers.

References (6)

T. Hirokawa et al.
J. Chromatogr.
(1982)
T. Hirokawa et al.
J. Chromatogr.
(1982)
F.M. Everaerts et al.
(1976)

There are more references available in the full text version of this article.

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Complex-forming equilibria in isotachophoresis : IV. Simulation of isotachophoretic equilibria of metal ions forming multi-coordinated complexes

Abstract

J. Chromatogr.

J. Chromatogr.