A polymer-based zwitterionic stationary phase for hydrophilic interaction chromatography

We describe a novel polymer-based zwitterionic stationary phase for hydrophilic interaction chromatography (HILIC). It is prepared by chemical modification of poly (glycidyl methacrylate-divinylbenzene) (GMA-DVB) by converting epoxide groups of microsphere surface to diol groups via hydrolysis, then clicking cysteine onto the microsphere with pendant double bonds of microsphere surface via thiol-ene click chemistry. The phase has been characterized by scanning electron micrograph, elemental analysis and zeta potential measurement. Diol and zwitterionic group (carboxylate and amine group associated with cysteine) onto the surface of GMA-DVB microspheres make them possess good hydrophilicity, as supported by effective separation towards common polar analytes. It shows good stability at alkaline solution (e.g. pH 10) and negligible bleed (e.g. only 1.7-fold blank and similar to 55-fold lower than a commercial silica-based polar phase tested with the minimal bleed level). Such phase exhibits specific separation selectivity to ionic analytes and simultaneous separation of anions and cations is achieved in the retention order of I- < NO3- < Choline < Br- < Cl- < K+ < Na+.