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Development of High Efficiency and New Selectivity Liquid Chromatographic Phases for the Separation of Ionic and Hydrophilic Analytes Open Access

Descriptions

Other title
Subject/Keyword
packing
diazonium
suspensions
chromatography
carbon
Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
Wahab, Muhammad F
Supervisor and department
Lucy, Charles A. (Department of Chemistry)
Examining committee member and department
Campbell, Robert E. (Department of Chemistry)
Le, X. Chris (Department of Laboratory Medicine and Pathology)
Linford, Matthew R. (Department of Chemistry and Biochemistry, Brigham Young University)
McDermott, Mark T (Department of Chemistry)
Department
Department of Chemistry
Specialization

Date accepted
2013-09-28T19:38:10Z
Graduation date
2013-11
Degree
Doctor of Philosophy
Degree level
Doctoral
Abstract
Separation of low molecular weight ions and hydrophilic analytes is achieved by high performance ion chromatography (IC) and hydrophilic interaction liquid chromatography (HILIC). The goal of this thesis was three-fold: to increase the efficiency of IC separations by employing small particles; to develop new selectivity phases for HILIC; and to understand the factors that can lead to distorted peak shapes. Long columns packed with large polymeric particles (6.5-13 µm) still dominate IC. This work investigated 3 µm carbon clad zirconia to which benzene sulfonic acid was bonded using diazonium chemistry. A 5 cm agglomerated anion exchanger was developed by adsorbing polycationic latexes to the particle surface. The efficiencies achieved (~ 51,000 /m) were superior to those of commercial column (~ 22,500 /m). In addition to particle size, column packing process strongly affects the efficiency. Packing studies with sulfonated particles (4.4 µm) showed that dispersed slurries are desirable to avoid particle agglomeration. Dispersed suspensions exhibit shear thickening that can be overcome by heating the slurry during column packing. Near optimum (reduced plate height ~ 2) packing of agglomerated columns was achieved. These studies concluded that the colloidal and rheological aspects of microparticulates must be considered to optimize packing. A new class of HILIC phases was created by modification of porous graphitic carbon (PGC) using diazonium chemistry. The hydrophobic PGC surface was converted into a polar HILIC phase by attaching benzoic acid groups. This phase showed unusual selectivity, which was different from 35 stationary phases. The utility of the phase was demonstrated for separations of nucleotides, phenols, and carboxylic acids. Overloading a column reduces the separation efficiency and alters the peak shape from Gaussian peaks to fronted or tailed peak profiles. Studies with IC columns showed that if the eluent anion is more strongly retained than the analyte ion on an ion exchanger, the analyte peak is fronting. If the eluent is more weakly retained on the stationary phase, the analyte peak always tails under overload conditions. Overall, this work has enhanced the fundamental understanding in the column packing process and offered new materials for the separation of ionic and polar analytes.
Language
English
DOI
doi:10.7939/R37P8TM0Z
Rights
This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for the purpose of private, scholarly or scientific research. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
Citation for previous publication
M. Farooq Wahab, Mohammad. E. A. Ibrahim, Charles A. Lucy, Carboxylate Modified Porous Graphitic Carbon- A New Class of Hydrophilic Interaction Liquid Chromatography Analytical Chemistry, 2013, 85, 5684-91M. Farooq Wahab, Christopher A. Pohl and Charles A. Lucy, Colloidal Aspects and Packing Behaviour of Charged Microparticulates in High Efficiency Ion Chromatography, Journal of Chromatography A, 2012, 1270, 139-146M. Farooq Wahab, Christopher A. Pohl, Charles A. Lucy, Ion Chromatography on Carbon Clad Zirconia Modified by Diazonium Chemistry and Functionalized Latex Particles, Analyst, 2011, 136, 3113-3120.Charles A. Lucy and M. Farooq Wahab, Advances in Fast and High Resolution Ion Chromatography, LC-GC North America & EuropeLC-GC (Special Issue on Ion Chromatography), 31 (S4b) 38-42

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