Chiral microemulsion electrokinetic chromatography with two chiral components: Improved separations via synergies between a chiral surfactant and a chiral cosurfactant.
In this study, the combination of two chiral components in a microemulsion formulation for the separation of enantiomers via microemulsion EKC (MEEKC) was successfully accomplished. Previous publications of chiral microemulsions have utilized only one chiral entity; the surfactant, cosurfactant, or oil was chiral. This is the first study, to date, of the effects of using two chiral species in a single pseudostationary phase (PSP). The chiral surfactant dodecoxycarbonylvaline (DDCV) was used in conjunction with the chiral cosurfactant S-2-hexanol. Ethyl acetate was incorporated as the oil core of the microemulsion and the buffer was 50 mM phosphate at a pH of 7. Additionally, a microemulsion prepared with racemic 2-hexanol was used for comparison to a previous DDCV microemulsion and as a baseline for the newly formulated dual chiral microemulsion. The efficiencies, resolutions, and enantioselectivities for the S-2-hexanol, racemic 2-hexanol, and original 1-butanol DDCV microemulsions are compared. The hexanol-based PSPs provide improved efficiencies and resolutions. To evaluate the combination of each DDCV enantiomer (R and S) with S-2-hexanol, changes in Gibb's free energy were calculated. A synergistic effect was found when two chiral components were combined to form a microemulsion.
Kahle
Kimberly A
KA
Department of Chemistry, Drexel University, Philadelphia, PA 19104, USA.
Foley
Joe P
JP
D020001:1-Butanol / Q000737:chemistry; D002845:Chromatography / Q000379:methods; D019075:Electrophoresis, Capillary / Q000379:methods*; D004655:Emulsions; D004809:Ephedrine / Q000031:analogs & derivatives / Q000032:analysis; D000441:Hexanols / Q000737:chemistry*; D013237:Stereoisomerism; D013501:Surface-Active Agents / Q000737:chemistry*; D013816:Thermodynamics; D014633:Valine / Q000031:analogs & derivatives* / Q000737:chemistry
D004655:Emulsions; D000441:Hexanols; D013501:Surface-Active Agents; C104188:N-dodecoxycarbonylvaline; C041707:N-methylephedrine; D020001:1-Butanol; C037076:2-hexanol; D004809:Ephedrine; D014633:Valine