Thermodynamics of chiral selectivity in capillary electrophoresis: separation of ibuprofen enantiomers with β-cyclodextrin

The effect of temperature on the electrophoretic chiral separation of ibuprofen with β-CD was investigated. Background electrolytes with sodium acetate or formate were chosen because of their constant pK within 0.03 units in the temperature range 25–50°C. Ibuprofen has a temperature independent pK v...

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Bibliographic Details
Published in:Journal of Chromatography A 1997-12, Vol.792 (1-2), p.371-378
Main Authors: Reijenga, Jetse C, Ingelse, Benno A, Everaerts, Frans M
Format: Article
Language:English
Subjects:
Cyclodextrins
Ibuprofen
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Summary:The effect of temperature on the electrophoretic chiral separation of ibuprofen with β-CD was investigated. Background electrolytes with sodium acetate or formate were chosen because of their constant pK within 0.03 units in the temperature range 25–50°C. Ibuprofen has a temperature independent pK value of 4.36, and a mobility of 23.3·10−9 m2/Vs at 25°C. The mobility has a temperature coefficient of 2.0%/°C. At that same temperature, formation constants K1 for the uncharged enantiomers are 9955 and 10294 M−1 respectively. The formation constant K2 for the charged form is 5256 M−1 for both isomers. For these chiral formation constants, ΔH values are around −50 kJ/mol, whereas ΔS values are around −90 J/mol/K.
ISSN:0021-9673
DOI:10.1016/S0021-9673(97)00644-4