A new route for synthesis of N-methylimidazolium-grafted silica stationary phase and reevaluation in hydrophilic interaction liquid chromatography.

In this work, a "solvent-free" and green method for controllable and quantitative preparation of chromatographic stationary phase has been proposed. About the method, the largely excess of functional monomer and strict control of the proportion between silane and silica are the two most important points. Due to the existence of excessive functional monomer, silane can be utilized at the maximum extent, thereby achieving quantitative and reproducible bonding. Meanwhile, the excessive monomer can also be well recycled. By this new method, we controllably synthesized three Sil-MIm columns with various bonding amounts to investigate how the bonding amounts influence separation performances. The experiment results stated in some cases the columns with appropriate bonding amounts rather than maximum, were the best to fulfil some specific tasks. Meanwhile, it also demonstrated how important it was to control the bonding amounts of stationary phase.