ORCID Identifier(s)

0000-0002-7198-1163

Graduation Semester and Year

2017

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Chemistry

Department

Chemistry and Biochemistry

First Advisor

Daniel W Armstrong

Abstract

Chromatography using chiral stationary phases is the most effective and popular technique for qualitative and quantitative analysis of enantiomers in the pharmaceutical, agricultural, and food industry, among many others. Given the prevalence of chirality in nature, creation of new technologies for improving the speed and performance of chiral separations can provide immediate and significant benefits. This dissertation focuses on development of ultrahigh performance chiral phases which can provide separations at speeds that approach the speed of typical sensors and thereby enable chromatography as a real-time analysis tool. A variety of chiral selectors namely macrocyclic glycopeptides (teicoplanin, teicoplanin aglycone, vancomycin), cyclic oligosaccharides (derivatized cyclofructans, derivatized cyclodextrins), and cinchona anion exchangers (derivatized quinine) are utilized for their high-selectivity and versatility in operating under different chromatographic modes. Effects of bonding chemistry on selector performance is also studied. Superficially porous particles were chosen as stationary phase supports to exploit their high-efficiency, modest backpressure, and reduced retention in high-throughput separations. Once synthesized, stationary phase packing must be optimized to obtain high-efficiency columns. Fundamental studies on high-pressure slurry packing revealed the effects of non-Newtonian fluids and their impact on packed bed homogeneities. Several metrics were developed to qualitatively analyze the behavior of suspensions and successfully predict the type of bed that is likely to be formed. Effective and general slurry optimization techniques were developed to obtain high efficiencies and symmetric peak shapes. A novel peak shape analysis was also developed to identify and quantify concurrent fronting and tailing of peaks in order to optimize packing methods for modern high-efficiency stationary phase supports. Also studied were instrumental optimizations such as extra-column band broadening, detector artifacts and peak shape distortions, and frictional heat when operating at high flow rates. With high-efficiency and high-selectivity stationary phases and an optimized instrument, a plethora of sub-minute and sub-second separations were developed for chiral and achiral analytes. Further, application of resolution enhancement techniques such as segmented peak sharpening based on derivatives and extra-column band broadening correction through Fourier transform is demonstrated. For showcasing the ultimate capability of ultrahigh performance chiral phases, a sub-second separation of 10 peaks also is shown.

Keywords

High throughput separations, Chiral separations, Lliquid chromatography, Sub-second separations, Superficially porous particles

Disciplines

Chemistry | Physical Sciences and Mathematics

Comments

Degree granted by The University of Texas at Arlington

Included in

Chemistry Commons

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