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Modifier adsorption in supercritical fluid chromatography onto silica surface
Péter Vajda1, Georges Guiochon
1Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600, USA.
Journal of Chromatography. A
|August 3, 2013
Summary
Supercritical fluid chromatography separates alcohols using silica gel. Multilayer adsorption of methanol, ethanol, and isopropyl alcohol on silica gel from supercritical carbon dioxide was observed, impacting separation efficiency.
Area of Science:
- Analytical Chemistry
- Separation Science
- Materials Science
Background:
- Supercritical fluid chromatography (SFC) is a powerful separation technique.
- Silica gel is a common adsorbent used in chromatography.
- Understanding adsorption behavior is crucial for optimizing chromatographic separations.
Purpose of the Study:
- To investigate the adsorption of methanol, ethanol, and isopropyl alcohol on silica gel from supercritical carbon dioxide.
- To model the nonlinear adsorption isotherms of these alcohols.
- To elucidate the role of the adsorbed layer in SFC separations.
Main Methods:
- Nonlinear chromatographic techniques were employed.
- Frontal analysis was used to determine adsorption isotherm data points.
- A modified Brunauer-Emmett-Teller (BET) equation was used for modeling.
Main Results:
- Adsorption isotherm data for methanol, ethanol, and isopropyl alcohol were obtained.
- Nonlinear adsorption behavior was observed and successfully modeled.
- Evidence for the formation of an adsorbed multilayer of alcohols on the silica surface was found.
Conclusions:
- The formation of an adsorbed multilayer influences the separation of analytes in SFC.
- This understanding is applicable to both analytical and preparative SFC conditions.
- Silica gel's adsorption properties are key to its performance in SFC with these alcohols.
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