6533b857fe1ef96bd12b3918

RESEARCH PRODUCT

Porous zirconia and titania as packing materials for high-performance liquid chromatography

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Abstract Porous amorphous zirconia (ZrO 2 ) and titania (TiO 2 ) packings were synthesized as rigid microparticulate beads by means of a sol—gel process. Sufficient rigidity and desired mesoporosity of the ZrO 2 and TiO 2 particles were achieved only by a gel hardening process, followed by heat treatment. The mean pore diameter, p d , the specific surface area, a s , and the specific pore volume, ν p , were controlled by the heat treatment. Typical values were p d = 8 nm, a s = 80 m 2 /g and ν p = 0.23 ml/g. ZrO 2 - and TiO 2 -based revesed-phase packings were prepared by subjecting the native materials to a specific activation process and reaction with octadecyltrimethoxysilane. Native ZrO 2 and TiO 2 of graduated polarity, tested under normal-phase conditions, yielded a solvent strength series similar to those observed with silica and alumina. Retention of lipophilic analytes in n -heptane and dichloromethane was scarcely affected by the relative water content of the mobile phase. Native ZrO 2 and TiO 2 were found to be suitable for the separation of structural isomers. From calcined ZrO 2 and TiO 2 amines were eluted with totally symmetrical peaks when water-modified dichloromethane was used as the mobile phase. The retention and selectivity of n -octadecyl-bonded ZrO 2 and TiO 2 packings were identical with those of silica-based materials, except for showing a pronounced pH stability up to pH 12 in aqueous—organic mobile phases.