Preparation of an ionic liquid-functionalized polymer monolith and its application in the separation of Chinese herb with HPLC

A porous functionalized monolithic material based on ionic liquids (ILs) was produced through in situ polymerization within the confines of a stainless steel column (50x4.6mm i.d.). In the processes, 1-vinyl-3-butylimidazolium chlorine ionic liquid, 1-dodecylene, and butyl methacrylate were used as ternary monomers; ethylene dimethacrylate as the cross-linker; azobisisobutyronitrile as the initiator; and dodecanol as the porogen. The optimized monolith showed high permeability as 13.54x10(-14)m(2), and high porosity as 75.08%. Then, its chromatographic characteristic was estimated by being used as the stationary phase of high-performance liquid chromatography (HPLC) to separate the mixtures of aromatic series compounds. Finally, the monolith was used to separate gastrodin from Chinese herb gastrodia rhizome; benzene and biphenyl from the effluent water, respectively. The column efficiency of the obtained IL-based monolith was calculated by the gastrodin peak as 22,000 plates m(-1). Moreover, the repeatability of the method was studied with the RSDs calculated by retention times and peak areas of gastrodin peak as 0.79%, 1.23% (run-to-run, n=6) and 0.86%, 1.89% (column-to-column, n=6), respectively. The results confirmed that the produced monolith was successfully used as the stationary phase of HPLC to separate small molecules in real samples with high performance.