Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, 53210 Pardubice, Czech Republic.
J Chromatogr A. 2013 Jan 25;1274:97-106. doi: 10.1016/j.chroma.2012.12.003. Epub 2012 Dec 12.
We synthesized 8 polymethacrylate monolithic capillary columns using laurylmethacrylate functional monomer and various cross-linking monomers differing in the polarity and size. The efficiency of monolithic columns for low-molecular compounds significantly improved with increasing number of repeat non-polar methylene groups in the cross-linker molecules, correlating with greater proportion of small pores with size less than 50 nm. The best efficiency with HETP=25 μm for alkylbenzenes was achieved for columns prepared using hexamethylene dimethacrylate (HEDMA). Columns prepared with polar (poly)oxyethylene dimethacrylate cross-linkers show also improved efficiency with increasing chain length and generally better performance in comparison to the (poly)methylene dimethacrylate cross-linkers of comparable size, however with less apparent effects of the chain lengths on the pore distribution. The monolithic columns prepared with tetraoxyethylene dimethacrylate (TeEDMA) showed the best efficiency of all the columns tested, corresponding to HETP=15 μm (approx. 70,000 theoretical plates/m), show excellent column-to-column reproducibility with standard deviations of 2.5% in retention times, good permeability and low mass transfer resistance, so that is suitable for fast separation of low-molecular compounds in 2 min or less. By modification of the fused-silica capillary inner walls pre-treatment procedure, very good long-term stability was achieved even in 0.5 mm i.d. capillary format. The TeEDMA column can be also used for size-exclusion chromatography of lower non-polar synthetic polymers, whereas it is less suitable for separations of proteins than the HEDMA column.
我们合成了 8 种基于甲基丙烯酸月桂酯功能单体和不同极性和尺寸的交联单体的聚甲基丙烯酸酯整体毛细管柱。对于低分子量化合物，整体柱的效率随着交联分子中重复非极性亚甲基数量的增加而显著提高，这与小于 50nm 的小孔比例增加有关。使用六亚甲基二甲基丙烯酸酯（HEDMA）制备的柱可获得最佳的烷基苯分离效率（HETP=25μm）。具有极性（共聚）氧乙基二甲基丙烯酸酯交联剂的柱也表现出随着链长的增加而提高的效率，与具有可比尺寸的（共聚）亚甲基二甲基丙烯酸酯交联剂相比，通常具有更好的性能，但对孔径分布的影响不太明显。使用四氧乙烯二甲基丙烯酸酯（TeEDMA）制备的整体柱表现出所有测试柱中最好的效率，对应于 HETP=15μm（约 70,000 理论板/m），显示出极好的柱间重现性，保留时间的标准偏差为 2.5%，良好的渗透性和低传质阻力，因此适用于在 2 分钟或更短的时间内快速分离低分子量化合物。通过对熔融石英毛细管内壁预处理程序的修改，即使在 0.5mm id 的毛细管格式下也可以实现非常好的长期稳定性。TeEDMA 柱也可用于低非极性合成聚合物的尺寸排阻色谱，而与 HEDMA 柱相比，其不太适合蛋白质的分离。
