Title
Theory and Use of the Pseudophase Model in Gas−Liquid Chromatographic Enantiomeric Separations
Campus Units
Chemistry
Document Type
Article
Publication Version
Published Version
Publication Date
12-5-2005
Journal or Book Title
Analytical Chemistry
Volume
78
Issue
1
First Page
113
Last Page
119
DOI
10.1021/ac051289b
Abstract
The theory and use of the “three-phase” model in enantioselective gas−liquid chromatography utilizing a methylated cyclodextrin/polysiloxane stationary phase is presented for the first time. Equations are derived that account for all three partition equilibria in the system, including partitioning between the gas mobile phase and both stationary-phase components and the analyte equilibrium between the polysiloxane and cyclodextrin pseudophase. The separation of the retention contributions from the achiral and chiral parts of the stationary phase can be easily accomplished. Also, it allows the direct examination of the two contributions to enantioselctivity, i.e., that which occurs completely in the liquid stationary phase versus the direct transfer of the chiral analyte in the gas phase to the dissolved chiral selector. Six compounds were studied to verify the model: 1-phenylethanol, α-ionone, 3-methyl-1-indanone, o-(chloromethyl)phenyl sulfoxide, o-(bromomethyl)phenyl sulfoxide, and ethyl p-tolylsulfonate. Generally, the cyclodextrin component of the stationary phase contributes to retention more than the bulk liquid polysiloxane. This may be an important requirement for effective GC chiral stationary phases. In addition, the roles of enthalpy and entropy toward enantiorecognition by this stationary phase were examined. While enantiomeric differences in both enthalpy and entropy provide chiral discrimination, the contribution of entropy appears to be more significant in this regard. The three-phase model may be applied to any gas−liquid chromatography stationary phase involving a pseudophase.
Copyright Owner
American Chemical Society
Copyright Date
2006
Language
en
File Format
application/pdf
Recommended Citation
Pino, Veronica; Lantz, Andrew W.; Anderson, Jared L.; Berthod, Alain; and Armstrong, Daniel W., "Theory and Use of the Pseudophase Model in Gas−Liquid Chromatographic Enantiomeric Separations" (2005). Chemistry Publications. 302.
https://lib.dr.iastate.edu/chem_pubs/302
Comments
Reprinted (adapted) with permission from Analytical Chemistry 78 (2006): 113, doi:10.1021/ac051289b. Copyright 2006 American Chemical Society.