Department of Pharmaceutical and Medicinal Chemistry, School of Pharmacy, Friedrich Schiller University, Jena, Germany.
J Sep Sci. 2011 Jan;34(1):64-9. doi: 10.1002/jssc.201000616. Epub 2010 Nov 16.
A CEC weak cation-exchange monolith has been prepared by in situ polymerization of acrylamide, methylenebisacrylamide and 4-acrylamidobutyric acid in a decanol-dimethylsulfoxide mixture as porogen. The columns were evaluated by SEM and characterized with regard to the separation of diastereomers and α/β-isomers of aspartyl peptides. Column preparation was reproducible as evidenced by comparison of the analyte retention times of several columns prepared simultaneously. Analyte separation was achieved using mobile phases consisting of acidic phosphate buffer and ACN. Under these conditions the peptides migrated due to their electrophoretic mobility but the EOF also contributed as driving force as a function of the pH of the mobile phase due to increasing dissociation of the carboxyl groups of the polymer. Raising the pH of the mobile phase also resulted in deprotonation of the peptides reducing analyte mobility. Due to these mechanisms each pair of diastereomeric peptides displayed the highest resolution at a different pH of the buffer component of the mobile phase. Comparing the weak-cation exchange monolith to an RP monolith and a strong cation-exchange monolith different elution order of some peptide diastereomers was observed, clearly illustrating that interactions with the stationary phase contribute to the CEC separations.
一种 CEC 弱阳离子交换整体柱是通过丙烯酰胺、亚甲基双丙烯酰胺和 4-丙烯酰胺丁酸在癸醇-二甲基亚砜混合物中进行原位聚合制备的。通过 SEM 对柱子进行了评估，并对天冬氨酰肽的非对映异构体和 α/β-异构体的分离进行了表征。通过比较同时制备的几个柱子的分析物保留时间，证明了柱子的制备具有重现性。使用由酸性磷酸盐缓冲液和 ACN 组成的流动相实现了分析物的分离。在这些条件下，由于聚合物羧基的解离增加，EOF 也作为驱动力起作用，因此肽通过电泳迁移。由于这些机制，每一对非对映异构体肽在流动相的缓冲成分的不同 pH 值下都显示出最高的分辨率。将弱阳离子交换整体柱与 RP 整体柱和强阳离子交换整体柱进行比较，观察到一些肽非对映异构体的洗脱顺序不同，这清楚地表明与固定相的相互作用有助于 CEC 分离。
