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Enantiomeric separation of hydroxy acids and carboxylic acids by diamino‐β‐cyclodextrins (AB, AC, AD) in capillary electrophoresis
Author(s) -
Galaverna Gianni,
Paganuzzi Maria Cristina,
Corradini Roberto,
Dossena Arnaldo,
Marchelli Rosangela
Publication year - 2001
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/1522-2683(200109)22:15<3171::aid-elps3171>3.0.co;2-k
Subject(s) - chemistry , capillary electrophoresis , enantiomer , structural isomer , carboxylic acid , carboxylate , protonation , chiral derivatizing agent , chromatography , amino acid , electrophoresis , stereochemistry , organic chemistry , chiral column chromatography , ion , biochemistry
Selectively modified 6,6′‐dideoxy‐6,6′‐ L ‐diamino‐β‐cyclodextrins (AB, AC, AD) were successfully used as chiral selectors for the enantiomeric separation of hydroxy acids and carboxylic acids (in particular, phenoxyalkanoic acid herbicides) in capillary electrophoresis (CE). Chiral separations were obtained at a low selector concentration (1 m M ) with good enantioselectivity and resolution factors. Separations were optimized as a function of pH. The different position of the charged groups on the upper rim greatly influenced the separation, accounting for electrostatic interactions between the protonated amino groups of the cyclodextrins (CDs) and the carboxylate of the selectands. The best enantiomeric separation of hydroxy acids was obtained with the AC regioisomer, whereas carboxylic acids were well resolved only by the AB regioisomer. A recognition model is proposed, based on two‐dimensional nuclear magnetic resonance (2‐D NMR) experiments, in which the orientation of the guest in the inclusion complex is determined by the electrostatic interactions between the selectand and the CD upper rim.