CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
J Chromatogr A. 2013 Apr 19;1286:137-45. doi: 10.1016/j.chroma.2013.02.066. Epub 2013 Feb 28.
Hydrophilic interaction liquid chromatography (HILIC) has been widely used for separating polar compounds as a complement mode to reversed-phase liquid chromatography. The development of new stationary phases for HILIC is significant to improve the coverage of various polar and hydrophilic compounds. The present study described the preparation and application of novel imidazolium-based zwitterionic stationary phases. 1-Vinyl-3-(butyl-4-sulfonate) imidazolium was synthesized from 1-vinylimidazole and 1,4-butane sultone, then bonded to the surface of 3-mercaptopropyl modified silica particles (core-shell silica and totally porous silica) by "thiol-ene" click chemistry to obtain the resulting zwitterionic stationary phase with a positively charged imidazole ring and a negatively charged sulfonate group. The zwitterionic stationary phases exhibited good selectivity and favorable retention for a wide range of polar solutes (nucleosides, nucleic acid bases, benzoic organic acids, uric acid and its methyl derivatives, water-soluble vitamins) as compared to a bare silica column. The column efficiency could reach up to 100,000 theoretical plates/m with cytosine as the test solute. The retention changes of various types of test solutes were investigated under different chromatographic conditions including water content, pH, buffer salt concentration in mobile phase and column temperature. The results indicated that the retention of solutes on the stationary phase was the outcome of a mixed-mode retention mechanism (i.e. a combination of adsorptive and partitioning interactions). In conclusion, the new imidazolium-based zwitterionic stationary phases have shown excellent chromatographic behavior for a variety of polar solutes under HILIC mode, and have a great potential as a new type of stationary phases for HILIC.
亲水作用液相色谱（HILIC）已广泛用于分离极性化合物，作为反相液相色谱的补充模式。开发新型 HILIC 固定相对于提高各种极性和亲水性化合物的覆盖范围具有重要意义。本研究描述了新型咪唑鎓两性离子固定相的制备和应用。1-乙烯基-3-（丁基-4-磺酸酯）咪唑啉由 1-乙烯基咪唑和 1,4-丁烷砜通过“硫醇-烯”点击化学反应键合到巯基丙基改性硅胶颗粒（核壳硅胶和全多孔硅胶）表面上，得到带有正电荷的咪唑环和负电荷的磺酸酯基团的两性离子固定相。与裸硅胶柱相比，两性离子固定相表现出对广泛的极性溶质（核苷、核酸碱基、苯甲酸有机酸、尿酸及其甲基衍生物、水溶性维生素）的良好选择性和有利保留。使用胞嘧啶作为测试溶质时，柱效率可高达 100,000 理论板/m。在不同的色谱条件下（包括水含量、pH 值、流动相中的缓冲盐浓度和柱温）研究了各种类型的测试溶质的保留变化。结果表明，溶质在固定相上的保留是混合保留机制（即吸附和分配相互作用的组合）的结果。总之，新型咪唑鎓两性离子固定相在 HILIC 模式下对各种极性溶质表现出优异的色谱行为，作为 HILIC 的新型固定相具有很大的潜力。
