SURFACE MODIFIED ZIRCONIA IN ANALYTICAL CHROMATOGRAPHY

点击翻译按钮获取中文摘要

DESCRIPTION: The chief goal of this work is to develop a new class of stationary phases for analytical HPLC based on zirconia as the supporting substrate. These phases are possible due to the prior development in the investigator's laboratory of porous, monodispersed (5-10 micron) particles of zirconia of extraordinary chemical, mechanical, and thermal stability. Zirconia is a stable substrate that resists dissolution from pH 0-14, does not shrink or swell in any chromatographically interesting solvent or ionic strength and does not further sinter and thus loose pore volume or structure upon heating to 800-900 degree C. The essence of the present proposal is to develop, characterize, and apply a suite of different chemical surface modification processes designed to tailor the surface chemistry of zirconia. The investigator's goal is to make highly selective and efficient stationary phases for the separation of low molecular weight species especially those which are health hazards in the agrochemical workplace including: insecticides, herbicides, and their metabolites. The surface modification techniques of interest will focus primarily on the development of a carbon- clad zirconia made by chemical vapor deposition, thus using his considerable prior experience with carbon-coated materials. The investigator also proposes to make stable, monomer-like phases of zirconia analogous to silane-modified silica to achieve high chromatographic efficiency. The investigator will use the metal complexation chemistry between Zr(IV) and catechol and related compounds to do this. Additionally, he will explore the deposition of metals and metal oxides on zirconia to modify its surface chemistry. A major technical advantage of zirconia supports relative to conventional silanized silica supports, that makes much of the proposed work possible, is their very high thermal stability during sintering and when in contact with eluents. This allows the supports to be used without loss of stationary phase at temperatures well above 100 degree C, Such high temperatures not only provide narrower peaks due to enhanced intra- and inter-phase mass transfer but will also decrease the net volume of toxic organic waste produced during the separation. The P.I. feels that one of the most intriguing aspects of the proposed study is the extraordinary chromatographic selectivity of elemental carbon surfaces in the separation of stereo isomers of both polar and nonpolar solutes under reverse-phase conditions. He believes that this selectivity will be of major significance in the development of very fast, reliable and robust analytical methods for a wide array of agrochemical hazardous substances.