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Mechanistic studies on the separation of cations in zwitterionic ion chromatography


Cook, HA and Dicinoski, GW and Haddad, PR, Mechanistic studies on the separation of cations in zwitterionic ion chromatography, Journal of Chromatography A, 997, (1-2) pp. 13-20. ISSN 0021-9673 (2003) [Refereed Article]

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DOI: doi:10.1016 /S0021-9673(03)00063-3


Electrostatic ion chromatography, also known as zwitterionic ion chromatography, has been predominantly used for the analysis of anions. Consequently, separation mechanisms proposed for this technique have been based on anion retention data obtained using a sulfobetaine-type surfactant-coated column. A comprehensive cation retention data set has been obtained on a C18 column coated with the zwitterionic surfactant N-tetradecylphosphocholine (which has the negatively and positively charged functional groups reversed in comparison to the sulfobetaine surfactants), with mobile phases being varied systematically in the concentration and species of both the mobile-phase anion and cation. A retention mechanism based on both an ion exclusion effect and a direct (chaotropic) interaction with the inner negative charge on the zwitterion is proposed for the retention of cations. Despite the relatively low chaotropic nature of cations compared with anions, the retention data shows that cations are retained in this system predominantly due to a chaotropic interaction with the inner charge, analogous to anions in a system where the C18 column is coated with a sulfobetaine-type surfactant. The retention of an analyte cation, and the effect of the mobile-phase anion and cation, can be predicted by the relative positions of these species on the Hofmeister (chaotropic) series.

Item Details

Item Type:Refereed Article
Keywords:Electrostatic ion chromatography; Zwitterionic ion chromatography; Ion chromatography
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:Dicinoski, GW (Associate Professor Gregory Dicinoski)
UTAS Author:Haddad, PR (Professor Paul Haddad)
ID Code:27508
Year Published:2003
Web of Science® Times Cited:30
Deposited By:Chemistry
Deposited On:2003-08-01
Last Modified:2010-02-05

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