Novel highly hydrophilic zwitterionic monolithic column for hydrophilic interaction chromatography

Abstract A novel zwitterionic hydrophilic porous poly(SPV‐ co ‐MBA) monolithic column was prepared by thermal co‐polymerisation of 1‐(3‐sulphopropyl)‐4‐vinylpyridinium‐betaine (4‐SPV) and N , N ′‐methylenebisacrylamide (MBA). An HILIC/RP dual separation mechanism was observed on this optimised poly(SPV‐ co ‐MBA) monolithic column and the composition of the mobile phase corresponding to the transition from the HILIC to the RP mode was around 30% ACN in water. Higher hydrophilicity was achieved on this novel monolithic column compared to the poly( N , N ‐dimethyl‐ N ‐methacryloxyethyl‐ N ‐(3‐sulphopropyl)ammonium betaine‐ co ‐ethylene dimethacrylate) monolithic column. Permeability studies showed slight swelling and/or shrinking with mobile phases of different polarity. As might be anticipated, a weak electrostatic interaction for charged analytes was also observed by studying the influence of mobile phase pH and salt concentration on their retention on the poly(SPV‐ co ‐MBA) monolithic column. The final optimised poly(SPV‐ co ‐MBA) monolith showed comparable selectivities to commercial ZIC‐ p HILIC phases for polar test analytes. Fast separation of five pyrimidines and purines was achieved in less than 1 min due to the high permeability of the monolithic column. Additionally, baseline separation of nine benzoic acid derivatives was also observed using either a pH or ACN gradient.