Modifier adsorption in supercritical fluid chromatography onto silica surface

•Adsorption isotherms of light alcohols on silicagel from supercritical CO2 were measured.•Measurements were carried out by frontal analysis.•These isotherms fit well a modified BET equation for heterogeneous surfaces.•The results suggest the formation of adsorbed multilayers of these alcohols.•Thei...

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Bibliographic Details
Published in:Journal of Chromatography A 2013-08, Vol.1305, p.293-299
Main Authors: Vajda, Péter, Guiochon, Georges
Format: Article
Language:English
Subjects:
adsorbents
Adsorption
Alcohols
Analytical chemistry
carbon dioxide
Chemistry
Chromatographic methods and physical methods associated with chromatography
Chromatography
equations
ethanol
Ethyl alcohol
Exact sciences and technology
Frontal analysis
isopropyl alcohol
methanol
Modifier adsorption
Nonlinearity
Other chromatographic methods
Separation
silica
solvents
sorption isotherms
Supercritical fluid chromatography
Supercritical fluids
Surface chemistry
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Summary:•Adsorption isotherms of light alcohols on silicagel from supercritical CO2 were measured.•Measurements were carried out by frontal analysis.•These isotherms fit well a modified BET equation for heterogeneous surfaces.•The results suggest the formation of adsorbed multilayers of these alcohols.•Their adsorption energy distributions were also measured. The adsorption of methanol, ethanol and isopropyl alcohol on a silicagel adsorbent from supercritical carbon dioxide was investigated using nonlinear chromatographic techniques. Series of adsorption isotherm data points of these alcohols were determined by frontal analysis. Their nonlinear adsorption behavior were modeled using a modified BET equation extended for heterogeneous adsorption surfaces. Our results suggest the formation of an adsorbed multilayer of alcohols above the silica surface. This organic solvent enriched layer governs the separation of the analytes in supercritical fluid chromatographic separations, both under analytical and preparative conditions.
ISSN:0021-9673
DOI:10.1016/j.chroma.2013.06.075