Chromatographic properties of high-density octadecyl phases immobilized onhigh-purity silica gel

The chromatographic characteristics of a reversed phase based on spherical high-purity silica for the separation of diaminotoluenes and nitrobenzoic a cids were examined. It was found that this phase is superior to reversed ph ases commonly used for separating aromatic amines in properties. Diaminotol uene isomers were completely separated in the methanol-buffer solution and methanol-water systems. At the same time, compounds of an acidic nature wer e equally separated on phases of different types. The interaction of bases with silanol groups of the matrix makes a significant contribution to the r etention mechanism, regardless of the nature of the phase surface. However, this contribution is much smaller for a phase based on high-purity SiO2. S mall half-widths of the chromatographic peaks of strongly retained bases ob served for this phase are indicative of the absence of highly acidic silano l groups.