Reversed-phase liquid chromatography of proteins and peptides using multimodal copolymer-encapsulated silica

Multimodal copolymer-encapsulated particles for liquid chromatography were prepared by bonding 1-octadecene and unsaturated carboxylic acids on silica particles (5 mu m diameter, 300 Angstrom pores) for liquid chromatography of proteins. These multimodal copolymer-encapsulated particles can provide both hydrophobic and hydrogen bonding interactions with polar compounds. Th e chromatographic performance of these multimodal copolymer-encapsulated pa rticles for peptide and protein separations was evaluated under reversed-ph ase conditions. Compared with typical C-8-bonded silica, polymer-encapsulat ed particles were more stable in acidic mobile phases and provided better r ecoveries, especially for large proteins (M-r > 0.5.10(6)). Totally hydroph obic polymer-encapsulated particles were found to produce broad peaks for p roteins, and significant improvements were observed by introducing hydrophi lic groups (-COOH) onto the polymer-encapsulated surface to form a multimod al phase. For the reversed-phase liquid chromatography of peptides and prot eins, improved selectivity and increased solute retention were found using the multimodal polymer-encapsulated particles. More peaks were resolved for the separation of complex peptide mixtures such as protein digests using t he multimodal polymer-encapsulated particles as compared to totally hydroph obic polymer-encapsulated particles. (C) 2000 Elsevier Science B.V. All rig hts reserved.