Enantioseparation of Tröger's Base Derivatives by Capillary Electrophoresis Using Cyclodextrins as Chiral Selectors

Abstract

The enantioseparation of seven Tröger's base derivatives (TBs) was carried out by capillary electrophoresis using α-, β-, and γ-cyclodextrins as chiral selectors and phosphate at 20 mmol/l concentration, pH 2.5, as background electrolyte. The method was optimized with respect to the concentration of chosen chiral selectors (0-50 mmol/l) and the amount of organic solvent (acetonitrile, 0-25 % (v/v)) in the electrolyte. The results indicate that all the studied variables, i.e., type of chiral selector, its concentration, and the amount of the added organic solvent, have a significant impact on the enantioseparation of the studied TBs. The best results for the majority of the separated TBs were obtained utilizing β-cyclodextrin at 5 mmol/l concentration and with various amounts of acetonitrile added ranging from 5 to 15% (v/v) in the background electrolyte. For the two smallest studied TBs, γ-cyclodextrin with 10% (v/v) acetonitrile also provided good resolution.

The influence of the substituent position in monocarboxymethyl-γ-cyclodextrins on enantioselectivity in capillary electrophoresis

“…Some of these analytes, namely, primaquine , TB1 and TB2 have been separated previously utilizing a mixture of carboxymethylated α‐CDs, and TB1 employing a mixture of highly sulfated α‐CDs . Racemic mixtures of diperodon , mefloquine , primaquine , TB1 , TB2 , and tryptophan methyl ester have been successfully separated by native β‐CD and carboxymethylated β‐CDs. Tryptophan methyl ester enantiomers have also been resolved by heptakis(2,6‐di‐ O ‐methyl)‐β‐CD in CE mode.…”

“…Tryptophan methyl ester enantiomers have also been resolved by heptakis(2,6‐di‐ O ‐methyl)‐β‐CD in CE mode. Native γ‐CD has been previously used only for the enantioseparation of TB1 and TB2 and carboxymethylated γ‐CD only for the chiral separation of diperodon .…”

Nonaqueous Capillary Electrophoretic Enantioseparation of Water Insoluble Tröger's Base Derivatives Using β‐Cyclodextrin as Chiral Selector

“…The best results were obtained utilizing β‐cyclodextrin as chiral selector, sodium citrate (200 mmol/L), and Trizma (50 mmol/L) dissolved in formamide as electrolytes. Although TB derivatives 1 , 2 , 3 , and 5 have been successfully separated also by mixed aqueous‐organic CE previously, enantioseparation of TB derivatives 4 and 6 has been impossible by the latter technique due to insolubility of TB derivatives 4 and 6 in water. Thus, NACE represents a suitable alternative for enantioseparation of water‐insoluble analytes.…”

“…22 Some of these TB derivatives ( Fig. 1) have been previously separated in our group by aqueous capillary electrophoresis [28][29][30] and high-performance liquid chromatography (HPLC). 31…”

Chiral selectors in CE: Recent developments and applications (2012‐mid 2014)

“…β‐CD is used more often in chiral CE applications than the other native CDs due to its cavity size, which enables tight inclusion complex formation with most of the analytes . Song et al.…”