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Permanent link (DOI): https://doi.org/10.7939/R3WT1K
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Development and Characterization of New Stationary Phases for Hydrophilic Interaction Liquid Chromatography Open Access
- Other title
- Type of item
- Degree grantor
University of Alberta
- Author or creator
Ibrahim, Mohammed Elsayed Abdelatif
- Supervisor and department
Dr. Lucy, Charles A. (Chemistry)
- Examining committee member and department
Dr. Colon, Luis (Chemistry, The state University of New York at Buffalo)
Dr. Klassen, John (Chemistry, U of A)
Dr. Loppnow, Glen (Chemistry, U of A)
Dr. Curtis, Jonathan (Agricultural, life and environmental sciences, U of A)
Dr. Lucy, Charles A. (Chemistry, U of A)
Department of Chemistry
- Date accepted
- Graduation date
Doctor of Philosophy
- Degree level
Hydrophilic interaction liquid chromatography (HILIC) has gained high popularity among separation scientists in the last two decades due to its ability to retain polar analytes. Many new HILIC stationary phases with different selectivities have appeared in the recent literature. Such developments require tools which can classify and compare the selectivity of these HILIC columns. In this thesis, straightforward and simple selectivity plots were constructed and used to classify HILIC stationary phases into bare silica, zwitterionic, neutral and amine-based phases.
Silica monoliths show weak retention under HILIC conditions. In this thesis, the HILIC retention characteristics of silica monoliths were enhanced through surface modification with hydrophilic cationic latex nanoparticles. High efficiency (H ~ 25–110 µm) separations of carboxylic acids, amino acids and nucleotides were achieved. Due to their positive charge, the latex nanoparticles introduce anion exchange as another source of interaction. Consequently, these latex coated silica monoliths should exhibit mixed mode (HILIC/anion exchange) retention. Herein, the mixed mode retention of three different latex coated silica monoliths was studied. The AS9-SC latex coated silica monolith possessing the highest ion exchange capacity (44.1 µeq/column) separated six chaotropic and kosmotropic anions in less than 2.5 min.
Silica is chemically unstable under extreme pH conditions. On the other hand, porous graphitic carbon (PGC) has high pH stability. Being a hydrophobic material, typically usage of PGC is restricted to reversed phase chromatography. In the presented thesis, a carbon-based HILIC stationary phase was developed as a new class of HILIC stationary phases via diazonium chemistry. The potential of this phase (carboxylate-PGC) as a HILIC phase was demonstrated by separation of carboxylic acids, phenols, amino acids and nucleotides. Carboxylate-PGC phase showed different selectivity than 35 columns.
The efficiency of carbon-based phases is lower than silica due to slow mass transfer kinetics. Herein, we developed a hybrid phase comprising of 5 µm core-shell silica particles coated with 50 nm anionic carbon nanoparticles. This hybrid phase exhibited the unique selectivity of carbon and the high efficiency of core-shell silica particles. Fast and high efficiency HILIC separations of carboxylates and pharmaceuticals were achieved with efficiencies up to 85,000 plates/m.
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
- Citation for previous publication
Mohammed E. A. Ibrahim, Ting Zhou and Charles A. Lucy, “An agglomerated silica monolith for hydrophilic interaction liquid chromatography (HILIC) separations”, Journal of Separation Science, 33 (2010), 773-778.Mohammed E. A. Ibrahim and Charles A. Lucy, “Mixed mode HILIC/anion exchange separations on latex coated silica monoliths”, Talanta, 100 (2012), 313-319.Mohammed E. A. Ibrahim and Charles A. Lucy “Chapter Two: Stationary Phases for HILIC” in a textbook of the title of “Hydrophilic Interaction Chromatography-A guide for practitioners” edited by B.A. Olsen and B.W. Pack, Wiley, 2013, 43-85.M. Farooq Wahab, Mohammed E. A. Ibrahim and Charles A. Lucy, “Carboxylate modified porous graphitic carbon: A new class of Hydrophilic interaction liquid chromatography phases”, Analytical Chemistry, 85 (12) (2013), 5684–5691.
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File title: Cover Pages - IBRAHIM thesis 23th JAN 2014-Lucy