Preparation of Weak Cation Exchange Monolithic Capillary Column and Its Application for Protein Separation

A polymer-based capillary monolithic support was prepared by in situ copolymerization using glycidyl methacrylate (GMA) as monomer, ethylene dimethacrylate (EDMA) as crosslinking reagent, and a mixture of 1-propanol, 1,4-butanediol, and water as porogen solvent. The optimal ratio of above reactants in volume is GMA: EDMA: 1-propanol: 1,4-butanediol: water = 0.32:0.08:0.35:0.2:0.05. A macroporous monolithic support with 100–300 nm pore size was obtained under the reacting conditions of 24 h and 60 °C. The monolithic support was modified with iminodiacetic acid (IDA) and a weak cation-exchange capillary monolithic column was obtained. The optimal modifying conditions were: reaction time of 24 h, reaction temperature of 75 °C, and reaction pH value of 11.0. The three model proteins, albumin egg, trypsin, and lysozyme, could be separated on this weak cation-exchange capillary monolithic column with a length of only 50 mm within 13 min.