REDUCTION OF A QUANTITY OF STRONG ADSORPTION SITES BY A MODIFICATION OF SILICA SURFACE

The paper points out the differences among properties of silanols on a silica surface. Some silanols interact much stronger with adsorbed mo lecules than the remaining sites. The strongly interacting sites are u ndesirable on chromatographic materials. The paper shows how to block those strongly adsorbing silanols. Modification of the silica surface consists of two stages: adsorption of the modifier molecule and the re action with the adsorbing site. To get the satisfying results of modif ication with hexamethyldisilazane (HMDS) an equilibration time of 40 h between silica and the modifier is necessary.