CROSS-LINKED HYDROXY-AL-MONTMORILLONITE AS A STATIONARY PHASE IN LIQUID-CHROMATOGRAPHY

Quasi-sperhical particles (7-μm mean diameter) were prepared from cross-linked hydroxy-Al-montmorillonite by spray-drying. These particles were used as a packing material for columns in high-pressure liquid chromatography (HPLC). Aromatic phosphate esters, chlorosubstituted phenyl-ureas, monosubstituted benzenes, and the o-, m-, and p-isomers of di-substituted benzenes were separated on the columns, using isopropanol and hexane. Alkyl and alkoxy groups in the solute molecules sterically hindered the interaction of these molecules with the solid phase. Chromatographic data suggest that the strength of the interaction of phenolic groups with the solid phase increased with the acidity of these groups. Cross-linked hydroxy-Al-montmorillonite acted as a strong and selective adsorbent for many families of organic compounds. It was used successfully as the solid phase in HPLC separations with eluents ranging from nonpolar to highly polar. -from Authors