Cyclodextrin-Mediated Enantioseparation in Microemulsion Electrokinetic Chromatography

Abstract

Chiral separation by means of cyclodextrins has a long-standing tradition in capillary electrophoresis techniques. Here we present a chiral method utilizing the recently introduced microemulsion electrokinetic chromatography. The microemulsion consisting of 1.0% SDS, 4.0% 1-butanol, 3.0% 2-propanol, 0.5% ethylacetate, and 91.5% 20 mM phosphate buffer pH 2.5 serves as a pseudostationary phase which is complemented by sulfated cyclodextrin as a second phase. The analytes partition between the aqueous running buffer and both pseudostationary phases, the oil droplets and the cyclodextrins. Enantiomers are separated due to the formation of transient diastereomeric complexes with the cyclodextrins. For the racemates of ephedrine derivatives studied here sulfated β-cyclodextrin was successfully applied. The method is appropriate to resolve an entire series of chiral phenethylamines and can be used for separation of the racemates and impurity profiling, e.g., the determination of the enantiomeric excess.

New Trends in the Quality Control of Enantiomeric Drugs: Quality by Design-Compliant Development of Chiral Capillary Electrophoresis Methods

“…The use of additives to enhance/modulate CD-driven chiral separations has been known for a long time, and CD-modified micellar electrokinetic chromatography (CD-MEKC) [ 97 , 98 ] as well as CD-modified microemulsion electrokinetic chromatography (CD-MEEKC) [ 99 ] can be included in this strategy. Recently chiral ILs have been the focus of an intense interest as additives for their synergistic effect on CD-driven enantioseparations [ 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 ], and in some instances, for functionalization of the CDs [ 113 , 114 ].…”