Dubský Pavel, Tesarová Eva, Gas Bohuslav
Department of Physical Chemistry, Faculty of Science, Charles University, Prague, Czech Republic.
Electrophoresis. 2004 Feb;25(4-5):733-42. doi: 10.1002/elps.200305701.
When enantiomers separated by chromatography or capillary electrophoresis undergo interconversion reaction (enantiomerization) during the separation, it leads to a typical detection pattern: two individual peaks of the separated enantiomers are connected with a plateau consisting of a mixture of both separated enantiomers. We propose a separation method for determination of all individual rate constants (or inversion barriers) of the interconversion. The method enables to distinguish which part of interconversion takes place in the free (unbound) form of the analyte and which part in the complexed (bound) form. Further, we propose a complete dynamic model of capillary electrophoresis of interconverting enantiomers based on solving a complete set of continuity equations for all constituents of the separation system together with complexation and acid-base equilibria. This allows a simulation of both linear and nonlinear mode of separation and understanding all processes taking place in such enantioseparation systems. We demonstrate the applicability of the method on determination of the rate constants of interconversion of oxazepam enantiomers separated in systems with charged cyclodextrin chiral selectors.
当通过色谱法或毛细管电泳分离的对映体在分离过程中发生互变反应（对映体异构化）时，会产生一种典型的检测模式：分离出的对映体的两个独立峰与一个由两种分离出的对映体混合物组成的平台相连。我们提出了一种用于测定互变反应所有单个速率常数（或反转势垒）的分离方法。该方法能够区分互变反应的哪一部分是以分析物的游离（未结合）形式发生的，哪一部分是以络合（结合）形式发生的。此外，我们基于求解分离系统所有成分的完整连续性方程组以及络合和酸碱平衡，提出了互变对映体毛细管电泳的完整动力学模型。这允许对线性和非线性分离模式进行模拟，并理解在此类对映体分离系统中发生的所有过程。我们证明了该方法在测定在带有带电环糊精手性选择剂的系统中分离的奥沙西泮对映体互变速率常数方面的适用性。
