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Ultrashort partial‐filling technique in capillary electrophoresis for infinite resolution of tramadol enantiomers and its metabolites with highly sulfated cyclodextrins
Author(s) -
Rudaz Serge,
Le Saux Thomas,
Prat Josiane,
Gareil Pierre,
Veuthey JeanLuc
Publication year - 2004
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/elps.200406052
Subject(s) - enantiomer , capillary electrophoresis , chemistry , ionic strength , electrophoresis , cyclodextrin , chromatography , analyte , resolution (logic) , sulfation , analytical chemistry (journal) , stereochemistry , aqueous solution , biochemistry , artificial intelligence , computer science
The possibility to enhance resolution to infinite value in chiral capillary electrophoresis is attained as soon as the apparent mobility of one enantiomer becomes opposite to the other. This could be achieved on the basis of the carrier ability of multiple charged chiral selectors such as highly sulfated cyclodextrin (HS‐CD). With tramadol and its phase I metabolites selected as model compounds, the HS‐γ‐CD was found to be the most appropriate chiral selector. The CD concentration was determined where one enantiomer still migrated as a cation while the other migrated in the opposite side. Besides the chiral selector concentration, secondary parameters such as buffer concentration appeared to be critical to reach infinite resolution. The latter was achieved with partial filling technique using ultrashort separation zones (a few mm). In order to better understand the interaction mechanism between the selected CD and the analytes, the classical affinity capillary electrophoresis method, although not fully satisfactory because of ionic strength variations within a series of mobility shift measurements, was applied to estimate complexation constants and complex mobilities. The results obtained point to the prevailing role of complex mobility differences in the enantioselectivity mechanism.