Preparation Of Organically-inorganically Hybrid Zwitterionic Monolithic Column For Liquid Chromatography Using Pre-vinylization Silica Nanoparticles

An organically-inorganically hybrid zwitterionic monolithic column was prepared for liquid chromatography by in-situ polymerization of pre-vinylization silica nanoparticles,methacrylic acid(MAA)and 2-dimethylethylamine methacrylate(DAMA)in the presence of ternary porogens consisting of water,methanol and cyclohexanol in a 150 μm i.d.fused silica capillary(named silica-nanoparticles-containing hybrid monolithic column,SHM column).Under the conditions of different total monomer concentration,porogen composition,polymerization time and polymerization temperature,some SHM columns were prepared,and the preparation conditions was selected based on the SEM images and the pressure-vs-flowrate curves of the SHM columns.The polymerization mixture is composed of 7.5 mg of inorganic silica nanoparticles,11.5 μL of DAMA,11.5 μL of MAA,35 μL of cyclohexanol,17.5 μL of methanol,17.5 μL of water,and 0.2 mg of 2,2-Azobisisobutyronitrile;The polymerization time is 8 h;The polymerization temperature is 60℃.Then,the physical properties such as structural morphology,mechanical stability,permeability,column efficiency,swelling-shrinking behavior,preparation reproducibility of the SHM column were examined.Compared with the traditional zwitterionic monolithic column,the SHM monolithic column has the good features of easy preparation,good reproducibility,uniform pore structure,strong mechanical stability,high swelling resistance and high column efficiency.Finally,the influences of the composition,pH value,competitive ion concentration and organic additive content of mobile phase on chromatographic performance were investigated.After separation conditions were optimized,a group of inorganic anions was separated based on ion-exchange mechanism and a group of organic cations were separated based on a mixed mechanism of ion-exchange and hydrophilic interaction.