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A Mechanism of Separation in Electrostatic Ion Chromatography


Cook, HA and Hu, W and Fritz, J and Haddad, PR, A Mechanism of Separation in Electrostatic Ion Chromatography, Analytical Chemistry, 73, (13) pp. 3022-3027. ISSN 0003-2700 (2001) [Refereed Article]


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Copyright 2001 American Chemical Society - Reproduced by permission of The Royal Society of Chemistry (RSC)

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DOI: doi:10.1021/ac001442w


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.

Item Details

Item Type:Refereed Article
Research Division:Chemical Sciences
Research Group:Analytical chemistry
Research Field:Separation science
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the chemical sciences
UTAS Author:Cook, HA (Ms Helmy Cook)
UTAS Author:Hu, W (Mr Wei Hu)
UTAS Author:Fritz, J (Professor Jim Fritz)
UTAS Author:Haddad, PR (Professor Paul Haddad)
ID Code:22174
Year Published:2001
Web of Science® Times Cited:59
Deposited By:Chemistry
Deposited On:2001-08-01
Last Modified:2010-02-01
Downloads:655 View Download Statistics

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