Evaluation of chiral ionic liquids as additives to cyclodextrins for enantiomeric separations by capillary electrophoresis

Abstract

A great interest has been drawn these last years towards ionic liquids in analytical chemistry, especially for separation methods. Recent synthesis of chiral ILs opened the way of the evaluation of new potential selectors for enantiomeric separations. This work focused on the evaluation of two chiral ILs (ethyl- and phenylcholine of bis(trifluoromethylsulfonyl)imide) by CE. Particular selectivities are awaited by exploiting unique ion-ion or ion-dipole interactions and by tailoring the nature of the cation and the anion. To evaluate such phenomena, a study was carried out with anti-inflammatory drugs 2-arylpropionic acids as model compounds. The results show that these chiral ILs did not present direct enantioselectivity with regard to these model analytes. The influence of chiral ILs in the electrolytes was then studied in the presence of classical chiral selectors (di- or trimethyl-beta-cyclodextrin). Although no general trend could be established, an increase in separation selectivity and resolution was observed in some cases, suggesting synergistic effects. The complementary determination of apparent inclusion constant values of these IL cations in the used cyclodextrins by affinity CE provided support to the understanding of the phenomena involved.

Ionic Liquids in Separation Techniques

“…Authors claim that interaction of the acidic analytes with the cationic headgroup of chiral selectors contribute to observed the chiral recognition. Addition of chiral ILs could also improve enatioseparation using another chiral selector (Francois et al, 2007;Tran & Mejac, 2008 …”

New applications of cyclodextrins in electrically driven chromatographic systems: a review

“…Antiinflammatory drugs and 2-arylpropionic acids were applied as model analytes. It was established that the simultaneous addition of both types of chiral selectors increased the separation efficacy and resolution (Francois et al, 2007). The enantiomers of ibuprofen in human serum and urine were separated and quantitatively determined by CE.…”

Functionalized assembly of solid membranes for chiral separation using polyelectrolytes and chiral ionic liquid

“…For example, Francois et al have studied the influence of chiral ILs in the electrolytes for capillary electrophoresis (CE) in the presence of classical chiral selectors (diortrimethyl-_-cyclodextrin). 16 They observed an increase in separation selectivity and resolution and, in some cases, possible synergistic effects. Tran N]A) can be successfully used both as a co-electrolyte and as a chiral selector for CE.…”