Gatschelhofer Christina, Mautner Agnes, Reiter Franz, Pieber Thomas R, Buchmeiser Michael R, Sinner Frank M
Institute of Medical Technologies and Health Management, Joanneum Research, Auenbruggerplatz 20/3, A-8036 Graz, Austria.
J Chromatogr A. 2009 Mar 27;1216(13):2651-7. doi: 10.1016/j.chroma.2008.11.006. Epub 2008 Nov 7.
Functionalized monolithic columns were prepared via ring-opening metathesis polymerization (ROMP) within silanized fused silica capillaries with an internal diameter of 200 microm by in situ grafting. This procedure is conducted in two steps, the first of which is the formation of the basic monolithic structure by polymerization of norborn-2-ene (NBE) and 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo,endo-dimethanonaphthalene (DMN-H6) in a porogenic system (toluene and 2-propanol) using RuCl(2)(PCy(3))(2)(CHPh) as ROMP initiator. In the second step the still active initiator sites located on the surface of the structure-forming microglobules were used as receptor groups for the attachment ("grafting") of functional groups onto the monolithic backbone by flushing the monolith with 7-oxanorborn-2-ene-5,6-carboxylic anhydride (ONDCA). Functionalization conditions were first defined that did not damage the backbone of low polymer content (20%) monoliths allowing high-throughput chromatographic separations. Variation of the functionalization conditions was then shown to provide a means of controlling the degree of functionalization and resulting ion-exchange capacity. The maximum level of in situ ONDCA grafting was obtained by a 3h polymerization in toluene at 40 degrees C. The weak cation-exchange monoliths obtained provided good separation of a standard peptide mixture comprising four synthetic peptides designed specifically for the evaluation of cation-exchange columns. An equivalent separation was also achieved using the lowest capacity column studied, indicative of a high degree of robustness of the functionalization procedure. As well as demonstrably bearing ionic functional groups enabling analyte separation in the cation-exchange mode, the columns exhibited additional hydrophobic characteristics which influenced the separation process. The functionalized monoliths thus represent useful tools for mixed-mode separations.
通过原位接枝在内径为200微米的硅烷化熔融石英毛细管内，经由开环易位聚合反应（ROMP）制备了功能化整体柱。该过程分两步进行，第一步是在致孔体系（甲苯和2-丙醇）中，使用RuCl(2)(PCy(3))(2)(CHPh)作为ROMP引发剂，使降冰片-2-烯（NBE）和1,4,4a,5,8,8a-六氢-1,4,5,8-外向,内向-二亚甲基萘（DMN-H6）聚合形成基本的整体结构。第二步，通过用7-氧杂降冰片-2-烯-5,6-羧酸酐（ONDCA）冲洗整体柱，将位于构成结构的微球表面上仍具有活性的引发剂位点用作受体基团，用于将官能团附着（“接枝”）到整体主链上。首先确定了功能化条件，这些条件不会破坏低聚合物含量（20%）整体柱的主链，从而允许进行高通量色谱分离。然后表明，功能化条件的变化提供了一种控制功能化程度和所得离子交换容量的方法。通过在40℃下于甲苯中进行3小时聚合，获得了原位ONDCA接枝的最大水平。所得到的弱阳离子交换整体柱对包含四种专门设计用于评估阳离子交换柱的合成肽的标准肽混合物提供了良好的分离效果。使用所研究的最低容量柱也实现了等效的分离，这表明功能化过程具有高度的稳健性。除了明显带有能够以阳离子交换模式进行分析物分离的离子官能团外，这些柱还表现出额外的疏水特性，这影响了分离过程。因此，功能化整体柱是用于混合模式分离的有用工具。
