| Scope and method of study. The objectives of this research are (i) to synthesize zirconia and silica microparticles of controlled size, (ii) to introduce reproducible and well structured surface modification to form various stationary phases, and (iii) to evaluate the chromatographic properties of these novel packing materials and their practical applications in the separation of a wide variety of species. The polymerization conditions were evaluated for the synthesis of monodispersed, microspherical zirconia and silica particles that are suitable for high performance column liquid chromatography as packing materials. The silica phases served as reference materials to which zirconia-based stationary phases could be compared in terms of performance. The zirconia and silica particles were modified through covalent attachment of functional groups to the support surface to form a variety of stationary phases. Octadecylsilane compounds were used to form reversed-phase stationary phases. With zirconia support, polar bonded stationary phases for hydrophilic interaction chromatography were formed by either the covalent attachment of amino silane compounds or tetraethylenepentamine through {dollar}gamma{dollar}-glycidoxypropyltrimethoxysilane. Ion exchange stationary phases of different degree of charge density were synthesized on zirconia surface, and evaluated in the separation of proteins. The potentials of these zirconia- and silica-based stationary phases for applications in the life sciences were investigated with standard solutes such as dansyl amino acids, bioactive peptides, proteins, nucleic acids, oligosaccharides, etc.; Findings and conclusions. The various studies have demonstrated that microspherical zirconia support can be converted, via appropriately chosen and well controlled surface modification, into useful bonded stationary phases for various modalities of chromatography. The zirconia bonded stationary phases are chemically stable over a wide range of mobile phase pH conditions. The superior mechanical and chemical stability of zirconia column packing materials offers greater flexibility in choosing operational conditions that can enhance the selectivity and resolution in chromatographic separations. As with other supports, e.g. silica, the residual adsorptivities of zirconia support can be minimized via surface chemistry and/or mobile phase additives. In some instances, the residual adsorptivities, when moderate, may be beneficial for the separation. Analytical application studies with zirconia- and silica-based stationary phases have proved that these novel phases are useful for the high resolution and rapid separation of a variety of species. |
