Anomalous bandspreading of ethylenediaminetetraacetato—chromium(III) ion in reversed-phase high-performance liquid chromatography
1991; Elsevier BV; Volume: 545; Issue: 1 Linguagem: Inglês
10.1016/s0021-9673(01)88701-x
ISSN1873-3778
AutoresJohn H. Knox, Masami Shibukawa,
Tópico(s)Chemical and Physical Properties in Aqueous Solutions
ResumoAs part of a more general study of the high-performance liquid chromatography of ethylenediaminetetraacetate (EDTA) complexes of transition metal ions, it was noted that the EDTA complex of chromium(III) (Cr(III)—edta) gave broad, but symmetrical, peaks in reversed-phase chromatography on alkyl-modified silica (Hypersil C8), whereas other metal—edta complexes exhibited normal narrow peaks. The plots against linear flow velocity for Cr(III)—edta are straight lines with slopes which depend strongly on the nature and the concentration of the electrolyte used as buffer. The results obtained are interpreted in terms of the Giddings' model for slow reactions leading to equilibration and indicate that the relative slowness of ligand substitution reactions of Cr(III)—edta with anions in the mobile phase and stationary phases is the dominant contributor to the axial dispersion of this solute. Rate constants and activation energies for ligand substitution are estimated.
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