University of Tasmania
Browse

File(s) under permanent embargo

A Mechanism of Separation in Electrostatic Ion Chromatography

Version 2 2023-06-23, 11:06
Version 1 2023-05-26, 11:40
journal contribution
posted on 2023-06-23, 11:06 authored by HA Cook, W Hu, J Fritz, Paul HaddadPaul Haddad
The retention mechanism of electrostatic ion chromatography (EIC) is currently under debate and is the focus of this paper. A comprehensive set of retention data has been obtained on a C18 column coated with the zwitterionic surfactant 3-(N,N-dimethylmyristylammonio)propanesulfonate used with a range of mobile phases in which both the mobile-phase anion and cation have been varied systematically. Electro-osmotic flow measurements were also obtained on fused-silica capillaries coated with the zwitterion (and also some monofunctional surfactants) and were used to evaluate the nature of the surface charge on the layer of adsorbed surfactant in the presence of various background electrolytes. A new retention mechanism for EIC was developed on the basis of these data. This mechanism proposes that equilibration of the bound zwitterions with a mobile phase containing a suitable electrolyte causes the establishment of a charged layer created by the terminal sulfonate groups of the zwitterion, which acts as a Donnan membrane. The magnitude and polarity of the charge on this membrane depends on the nature of the mobile-phase ions. The Donnan membrane exerts weak electrostatic repulsion or attraction effects on analyte anions. A second component of the retention mechanism is chaotropic interaction of the analyte anion with the quaternary ammonium functional group of the zwitterion. This interaction exerts the major effect on the separation selectivity of EIC, such that analyte anions are eluted in order of increasing chaotropic interactions in accordance with the Hofmeister series.

History

Publication title

Analytical Chemistry

Volume

73

Issue

13

Article number

13

Number

13

Pagination

3022-3027

ISSN

0003-2700

Department/School

Chemistry

Publisher

Amercian Chemical Society

Publication status

  • Published

Rights statement

Copyright Copyright 2001 American Chemical Society.

Repository Status

  • Restricted

Socio-economic Objectives

280105 Expanding knowledge in the chemical sciences

Usage metrics

    University Of Tasmania

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC