Abstract (US RE 34910, US 5346619):
This technology provides a composite support material that is useful as a stationary phase in liquid chromatography, particularly in high-performance liquid chromatography. The composite support material comprises carbon-clad particles of zirconium oxide (also referred to as ZrO2, or as "zirconia").?Advantageously, the carbon-clad ZrO2 particles display very high physical and chemical stability in aqueous media of high pH, e.g., pH 14. At these conditions, the particles are substantially resistant to dissolution of both the carbon cladding and the underlying ZrO2, and provide substantially constant solute retention during exposure to increasing amounts of alkaline mobile phase.

Technology Benefits:
Carbon-clad ZrO2 particles display very high physical and chemical stability in aqueous media of high pH, e.g., pH 14. At these conditions, the particles are substantially resistant to dissolution of both the carbon cladding and the underlying ZrO2, and provide substantially constant solute retention during exposure to increasing amounts of alkaline mobile phase.

Technology Uniqueness:
Carbon-clad ZrO2 material is useful as a stable reversed-phase chromatographic support material. Advantageously, the selectivity for polarizable solutes and hydroxyl solutes can be exploited to separate these species. The loading capacity of the support for these species can be adjusted, if required, by proper selection of the support material (i.e., pore size and specific surface area) and column size (overall capacity).
The carbon cladding is useful as a covering or masking agent for the ZrO2 surface. ZrO2 surfaces are known to interact strongly with carboxylic acids, sulfonates, phosphates, and the like. These interactions can lead to undesirable behaviors in chromatography applications. Although some residual ZrO2 sites may still remain exposed after the carbon cladding, substantially all of the surface is covered with a carbon cladding whose retentivity can be controlled more easily than the retentivity of bare ZrO2. Improvement of the coating and/or optimization of the pore geometry together with this technology may be used to produce a uniform hydrophobic coating to "seal" the ZrO2 surface.

Intellectual Property Summary:
Patent No. US RE 34910
Patent No. US 5346619