ACTIVATED SILICA SUPPORTS FOR PREPARATION OF CHROMATOGRAPHIC SORBENTS- A COMPARATIVE-STUDY OF SILICAS CONTAINING ATTACHED EPOXY, TOSYLOXY AND HALOGEN GROUPS

A comparative study of silica sorbents with attached epoxy, tosyloxy a nd halogen groups is presented. Epoxy-activated sorbents are shown to have the lowest concentration of attached functional groups among the activated sorbents studied. The low content of epoxy groups is suggest ed to originate from the partial destruction of epoxy rings during the modification of silica. New methods of epoxidation without the use of epoxysilanes and tosylation without the use of tosyl chloride are pro posed. Haloalkyl-activated sorbents are shown to have the highest cont ent of attached functional groups in a bonded layer. It is suggested t hat haloalkyl-activated sorbents are the most promising for the prepar ation of sorbents with high loadings of immobilized ligands.