BASE STABLE AND COMPOSITE CERAMIC SUPPORTS FOR HPLC

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The objective of this work is to develop an entirely new family of supports for use in analytical and preparative scale separating. While we will emphasize the use of these novel supports for biomolecules, they will, because of their unique surface chemistry, be of extraordinary utility for separating low molecular weight analytes. All of this work is based on the use of highly porous (50%). widepore (up to 1000Angstroms), microspheres of zirconia (ZrO2) and submicron colloids of ZrO2. ZrO2 has unsurpassed stability towards harsh chemical environments. While we have used it to separate many types of small molecules, unmodified ZrO2 (like unmodified silica) is not useful for the separation of proteins. Nonetheless, due to the vastly different surface chemistry of ZrO2 relative to silica, we are convinced that the oxide can be tailored to almost any desired use either by chemically reacting it with various inorganic species (such as phosphates), or by pretreating it with fluoride ion, or by cladding it with elemental carbon or other inorganic species via chemical vapor deposition. Most generally, the surface can be modified by coating it with virtually any polar or nonpolar polymer so as to make reversed-phase, hydrophobic interaction and ion exchange surfaces. Since very little is known about any of these novel substrates, we will also conduct fundamental studies of their surface chemistry by ESCA, SIMS, DRIFTS and MAS solid state NMR spectroscopies. Additionally, by using the irreversible adsorption of organophosphates and proteins at neutral pHs, we have made regeneratable affinity chromatographic supports in situ. Adsorption of any proteins can be reversed by passing pH 13-14 mobile phases over the ZrO2 to strip all adsorbed material without any damage to the substrate. Although alumina-based supports are severely damaged by such harsh treatment, using the extreme chemical and thermal stability of ZrO2 we will also develop methods for selective adsorption of pyrogenic lipopolysaccharides and the removal of nucleic acids from protein containing mobile phases. Extensive phosphate and fluoride treatment of the surface yields a chemically and mechanically stable material that has many of the highly desirable characteristics of calcium hydroxy apatite (HA) for the separation of proteins, but which unlike HA, can be used routinely at both low and high pH. In addition to the use of ZrO2 in column chromatography and batch adsorbers, magnetically stabilized fluidized bed separators will be made by incorporating ferromagnetic centers in ZrO2.