Capillary methacrylate-based monoliths by grafting from/to γ-ray polymerization on a tentacle-type reactive surface for the liquid chromatographic separations of small molecules and intact proteins

- Capillary methacrylate-based monoliths were synthesized with tentacle-type inner wall activation.
- Both thermal and radiolytic polymerization were employed.
- Monoliths were characterized by FT-IR, solid state NMR, NMR cryoporosimetry, and SEM.
- High efficiencies for separations of small molecules in isocratic mode and proteins in gradient elution were achievable.
- Thermal and radiolytic monoliths were compared in terms of morphology and chromatographic behaviours.

Capillary methacrylate-based monoliths were prepared for the high performance liquid chromatography (HPLC) separation of both small molecules and large biomolecules. An efficient grafting from/to synthetic approach was adopted introducing a network of activated sites in the inner wall surface using the new silanization agent (N-trimethoxysilylpropyl)-polyethylenimine. Copolymerization of lauryl methacrylate monomer and 1,6-hexanediol dimethacrylate cross-linker in the presence of porogenic solvents was obtained under continuous γ-ray exposure with high conversion yield.The morphology and porous structure of the resulting monoliths have been investigated by Scanning Electron Microscopy (SEM) and 1H NMR cryoporosimetry. By chromatographic investigation, the new capillary columns attested high kinetic performance (with efficiency larger than 100,000 theoretical plate/m for small molecules at optimum mobile phase linear velocity of about 0.5 mm/s) and also excellent mechanical stability and repeatability.The new methacrylate-based monolithic capillary columns have been successfully employed for efficient reversed-phase separation of intact proteins and peptides.