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Title:Design, synthesis, and evaluation of selectors and stationary phases for improved liquid chromatographic separations
Author(s):Welch, Christopher J.
Doctoral Committee Chair(s):Pirkle, William H.
Department / Program:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Chemistry, Analytical
Abstract:In this study a diverse array of research projects are presented, all having to do with the development of selectors and stationary phases for improved liquid chromatographic separations. Apart from the introductory material, two main topics are addressed: (1) the role of non-specific adsorption in chromatographic separations, and (2) the synthesis of selectors designed for recognition of particular analyte molecules.
In the introductory part of the thesis the use of 1,3,5-tri-t-butylbenzene as an improved void volume marker for several chiral stationary phases (CSPs) is described, as is a thermodynamic study investigating the role of solvation in a well characterized chiral recognition system.
The role of non-specific adsorption in chromatographic separations has been addressed for both the analyte and the stationary phase. A study of the effect of superfluous remote polar functionality on chiral recognition shows that polar groups not required in the chiral recognition process can have a deleterious effect on enantiomer separations by increasing retention and sometimes reducing enantioselectivity. The preparation of CSPs in which nonessential interaction sites have been eliminated leads to CSPs showing reduced retention and increased enantioselectivity.
An improved CSP designed for the non-steroidal anti-inflammatory drug, naproxen, is described in-five different studies. A "reciprocal" approach was used in this study, (S)-naproxen being immobilized to produce a CSP which was used to screen potential naproxen selectors. This study revealed several key features important for the enantioselective recognition of naproxen, which were incorporated inio a novel selector and CSP displaying a high degree of enantioselectivity for underivatized naproxen. The underivatized enantiomers of a number of related drugs such as ibuprofen, ketoprofen, etc. are easily separable using this CSP.
Finally, the rational design of an improved selector and stationary phase for the carbon cluster buckminsterfullerene (C$\sb{60}$) is described. A tripodal selector containing three $\pi$-acidic aromatic rings for simultaneous multipoint interaction with the spherical analyte molecule was immobilized on silica to afford a stationary phase displaying a high degree of retention for buckminsterfullerene, and a large separation factor for separation of the C$\sb{60}$/C$\sb{70}$ mixture.
Issue Date:1992
Rights Information:Copyright 1992 Welch, Christopher J.
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9236621
OCLC Identifier:(UMI)AAI9236621

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