Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
J Chromatogr A. 2014 Feb 21;1330:40-50. doi: 10.1016/j.chroma.2014.01.020. Epub 2014 Jan 15.
In the present study, several geminal dicationic ionic liquids based on 1,4-bis(3-allylimidazolium)butane and 1,8-bis(3-allylimidazolium)octane in combination with different anions bromide and bis(trifluoromethanesulphonyl)imide were prepared and then bonded to the surface of 3-mercaptopropyl modified silica materials through the "thiol-ene" click chemistry as stationary phases for hydrophilic interaction chromatography (HILIC). Compared with their monocationic analogues, the dicationic ionic liquids stationary phases presented effective retention and good selectivity for typical hydrophilic compounds under HILIC mode with the column efficiency as high as 130,000 plates/m. Moreover, the influence of different alkyl chain spacer between dications and combined anions on the retention behavior and selectivity of the dicationic ionic liquids stationary phases under HILIC mode was displayed. The results indicated that the longer linkage chain would decrease the hydrophilicity and retention on the dicationic ionic liquid stationary phase, and while differently combined anions had no difference due to the exchangeability under the common HILIC mobile phase with buffer salt. Finally, the retention mechanism was investigated by evaluating the effect of chromatographic factors on retention, including the water content in the mobile phase, the mobile phase pH and buffer salt concentration. The results showed that the dicationic ionic liquids stationary phases presented a mixed-mode retention behavior with HILIC mechanism and anion exchange.
在本研究中，制备了几种基于 1,4-双(3-烯丙基咪唑基)丁烷和 1,8-双(3-烯丙基咪唑基)辛烷的偕二阳离子二价离子液体，并与不同的阴离子溴化物和双(三氟甲烷磺酰基)亚胺结合，然后通过“硫醇-烯”点击化学键合到 3-巯丙基改性硅胶材料的表面上，作为亲水相互作用色谱（HILIC）的固定相。与它们的单阳离子类似物相比，在 HILIC 模式下，二价离子液体固定相对典型的亲水化合物具有有效的保留和良好的选择性，柱效高达 130000 板/m。此外，展示了二价阳离子和组合阴离子之间不同的烷基链间隔对二价离子液体固定相在 HILIC 模式下保留行为和选择性的影响。结果表明，较长的连接链会降低二价离子液体固定相的亲水性和保留性，而不同组合的阴离子由于在常见的 HILIC 流动相中带缓冲盐的可交换性而没有差异。最后，通过评估色谱因素对保留的影响，包括流动相中的含水量、流动相 pH 值和缓冲盐浓度，研究了保留机制。结果表明，二价离子液体固定相表现出混合模式保留行为，具有 HILIC 机制和阴离子交换。
