Diluted modified cyclodextrins as chiral stationary phases – influence of the polysiloxane solvent: Heptakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin |
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Authors: | Armin Dietrich Birgit Maas Armin Mosandl |
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Abstract: | The influence of different polysiloxane solvents on the efficiency and stereoselectivity of columns coated with mixtures of heptakis (2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin and the polysiloxanes was investigated. Generally, the enantioselectivity increased with decreasing polarity of the silicone solvent and/or increasing cyclodextrin concentration, with some exceptions. Thermodynamic investigations showed that a change of the diluting phase or the cyclodextrin concentration affects entropy as well as enthalpy differences between the diastereomeric cyclodextrin/solute complexes. As a consequence, a certain cyclodextrin/polysiloxane combination is superior to another only at a particular temperature. |
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Keywords: | Enantioselective gas chromatography Heptakis (2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β -cyclodextrin Polysiloxanes Thermodynamic parameters |
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