STUDIES ON TEXTURE AND PROPERTIES OF POROUS-GLASS AND SILICA-GEL USED AS SUPPORTS FOR CHEMICALLY BONDED AMINO PHASES FOR HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Two different types of siliceous materials, glass beads with a controlled porosity (PG) and silica gel (SG), were studied. One important difference between SG and PG is the presence of metal atoms in the PG surface and in the bulk. The surface concentration of these metals can be easily enhanced by appropriate secondary thermal treatment, thereby creating new adsorption sites in the PG surface. This thermal treatment results in migration of residual metal oxides such as boron, sodium or aluminium towards the PG surface, thereby forming highly active centres. The increase in the surface heterogeneity and the changes in the texture of PG subjected to secondary thermal treatment are responsible for the differing physico-chemical properties of such materials. SG and PG were modified with mono- and trifunctional 3-aminopropylsilanes. Before and after chemical modification all the materials were characterized by nitrogen sorption, Fourier transform IR spectroscopy, cross-polarization magic angle spinning NMR spectroscopy, secondary ion mass spectrometry and elemental analysis. The chromatographic properties of the modified PG phases were compared with those of the corresponding SG phases. © 1990.