Department of Chemistry, Drexel University, Philadelphia, PA 19104, USA.
Electrophoresis. 2009 Aug;30(16):2829-36. doi: 10.1002/elps.200800828.
The use of chiral pseudostationary phases in EKC provides high efficiencies and excellent resolution for enantiomeric separations. The chiral pseudostationary phases of interest in this study are alcohol-modified ("swollen") micelles, in which a co-surfactant (medium chain-length alcohol) is added with the surfactant. In this study, the chiral surfactant, dodecoxycarbonylvaline (DDCV), along with the co-surfactant, 2-hexanol, has been prepared as swollen micelle in order to investigate the chiral separation of enantiomeric pairs. Three sets of experiments were investigated in which swollen micelle systems contained: chiral surfactant and racemic co-surfactant; chiral surfactant and chiral co-surfactant; and phase ratio increases, in which both chiral surfactant and chiral co-surfactant were employed. In the first two sets of experiments, co-surfactant concentration was held constant and the surfactant concentration was increased. In the third set of experiments, both surfactant and chiral surfactant concentrations were increased proportionally. The chromatographic figures of merit for each enantiomeric pair were investigated and compared with various chiral aggregate systems. In swollen micelle compositions using constant racemic 2-hexanol concentration, when DDCV concentration increased, enantioselectivity and resolution increased; whereas, efficiency remained constant for most of the test compounds. Compositions using constant S-2-hexanol concentration reached a maximum in all chromatographic figures of merit when DDCV concentration was increased from 2 to 3%. An increase in both surfactant and co-surfactant concentrations led to noisy baselines and chiral aggregates that were generally unstable in solution.
手性伪固定相在 EKC 中的应用为对映体分离提供了高效率和出色的分辨率。本研究中感兴趣的手性伪固定相是醇改性（“溶胀”）胶束，其中添加了助表面活性剂（中链醇）。在这项研究中，手性表面活性剂十二烷氧羰基缬氨酸（DDCV）与助表面活性剂 2-己醇一起制备为溶胀胶束，以研究对映体对的手性分离。研究了三组实验，其中溶胀胶束体系包含：手性表面活性剂和外消旋助表面活性剂；手性表面活性剂和手性助表面活性剂；以及相比例增加，其中均使用手性表面活性剂和手性助表面活性剂。在前两组实验中，保持助表面活性剂浓度不变，增加表面活性剂浓度。在第三组实验中，手性表面活性剂和手性表面活性剂浓度按比例增加。研究了每个对映体对的色谱优点，并与各种手性聚集体系统进行了比较。在使用恒定外消旋 2-己醇浓度的溶胀胶束组成中，当 DDCV 浓度增加时，对映选择性和分辨率增加；而对于大多数测试化合物，效率保持不变。当 DDCV 浓度从 2%增加到 3%时，使用恒定 S-2-己醇浓度的组成在所有色谱优点中均达到最大值。表面活性剂和助表面活性剂浓度的增加导致基线噪音和手性聚集体不稳定。
