CP MAS NMR INVESTIGATIONS OF SILICA-GEL SURFACES MODIFIED WITH AMINOPROPYLSILANE/

Aminopropyl chemically bonded phases for high performance liquid chrom atography (HPLC) have been prepared using mono- and trifunctional meth oxy- or ethoxysilanes. Three types of silica gel with different surfac e characteristics were used as support for the chemically bonded phase s (CBPs). Surface characteristics of the packings before and after che mical modification were determined by porosity parameters, elemental a nalysis and CP/MAS NMR spectroscopy. Si-29 and C-13 CP/MAS NMR investi gations gave informations about different interactions between aminosi lyl ligands and/or these ligands and/or water molecules condensed in t he pores of the silica gel surface. With decreasing pore diameter of t he silica gel the proportion of protonated aminopropyl ligand increase s.