Institute of Polymer Chemistry, Johannes Kepler University Linz, Welser Strasse 42, A-4060 Leonding, Austria.
J Chromatogr A. 2010 Aug 13;1217(33):5389-97. doi: 10.1016/j.chroma.2010.06.021. Epub 2010 Jun 12.
Macroporous monolithic poly(butyl methacrylate-co-ethylene dimethacrylate) stationary phases were synthesized in the confines of 100 microm I.D. fused-silica capillaries via a free radical copolymerization of mono and divinyl monomeric precursors in the presence of porogenic diluents. These columns were used in order to determine their suitability for the reversed-phase separation of small molecules in isocratic nano-LC mode. Carefully designed experiments at varying realized phase ratio by a terminated polymerization reaction, as well as content of organic modifier in the mobile phase, address the most significant parameters affecting the isocratic performance of these monoliths in the separation of small molecules. We show that the performance of methacrylate-based porous polymer monoliths is strongly affected by the retention factor of the analytes separated. A study of the porous and hydrodynamic properties reveals that the actual nature of the partition and adsorption of the small analyte molecules between mobile and stationary (solvated) polymer phases are most crucial for their performance. This is due to a significant gel porosity of the polymeric stationary phase. The gel porosity reflects stagnant mass transfer zones restricting their applicability in the separation of small molecules under conditions of strong retention.
大孔整体聚（甲基丙烯酸丁酯-二乙烯基苯）固定相通过在致孔稀释剂存在下，单和二乙烯基单体前体的自由基共聚，在 100μmID 的熔融硅毛细管中合成。这些柱子被用于确定它们在小分子反相分离中的适用性，以等度 nano-LC 模式。通过终止聚合反应和在流动相中有机改性剂的含量来改变实际的相比例的精心设计的实验，解决了影响这些小分子分离中整体性能的最重要参数。我们表明，基于甲基丙烯酸酯的多孔聚合物整体柱的性能受分离的分析物的保留因子强烈影响。对多孔和流体力学性质的研究表明，小分子分析物分子在流动相和固定相（溶剂化）聚合物相之间的分配和吸附的实际性质对其性能至关重要。这是由于聚合物固定相具有显著的凝胶孔隙率。凝胶孔隙率反映了停滞的传质区，限制了它们在强保留条件下分离小分子的适用性。
