title: An approach to the determination of the enantiomeric excess at the extreme case by capillary electrophoresis.
abstract: Capillary electrophoresis (CE) has been applied to determine the percentage of enantiomeric excess (ee%) of chiral compounds. In such assays, the quality of chiral selectors (CSs) plays vital roles in resolving the enantiomers for accurate determination of the ee%. Selecting an efficient CS is usually by trial and error, and is, if ever possible, time-consuming and costly. Here we propose a new approach by using the velocity gap mode of CE (VGCE) method, to simplify the method development process for ee% determination. With VGCE, it is still possible to measure ee% even when the CS has a weak resolving power. This is especially important at the extreme cases where one of the enantiomers is significantly higher than the other one. The key point of VGCE in this case is to fractionate the small part of the mixture containing both enantiomers from the major component of the enantiomer, which is already enantiopure. Baseline separations can be achieved between the two enantiomers for the small mixture due to less longitudinal dispersion, making it possible to determine the ee%. The feasibility of this VGCE approach was confirmed by the ee% measurements of amlodipine and ofloxacin, respectively. And the practical application of VGCE was tested by analyzing levamlodipine besylate tablet.
authors.affiliation: Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, China.
authors.forename: Hongting
authors.initials: H
authors.lastname: Xiao
authors.affiliation: Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Fu
authors.affiliation: Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Liang
authors.affiliation: Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China.
authors.forename: Youxin
authors.initials: Y
authors.lastname: Li
authors.affiliation: Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China. Electronic address: bao@tju.edu.cn.
authors.forename: James J
authors.initials: JJ
authors.lastname: Bao
authors.affiliation: Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, China; Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China. Electronic address: yongz@tju.edu.cn.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D017311:Amlodipine / Q000032:analysis*; D019075:Electrophoresis, Capillary / Q000379:methods; D005240:Feasibility Studies; D009525:Niacin / Q000031:analogs & derivatives* / Q000032:analysis; D015242:Ofloxacin / Q000032:analysis*; D013237:Stereoisomerism; D013607:Tablets
chemical_list: D013607:Tablets; C542574:levamlodipine; D017311:Amlodipine; D009525:Niacin; D015242:Ofloxacin
keywords: Capillary electrophoresis; Chiral selector; Enantiomeric excess; Velocity gap mode