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New materials and techniques for miniaturised chromatography
Potter, OG (2011) New materials and techniques for miniaturised chromatography. PhD thesis, University of Tasmania.
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This thesis describes two bodies of work in which new methods were developed
to aid the miniaturisation and integration of chromatography.
The first body of work deals with the development of new stationary phases for
boronate affinity chromatography. Porous polymer monoliths were developed for
use as microscale boronate affinity extraction materials. The monoliths were
prepared in situ from poly(butyl methacrylate-co-ethylene dimethacrylate)
confined inside 100 μm ID fused silica capillaries. A 2-step sequential
photoinitiated grafting procedure was then used to create a layer of poly(glycidyl
methacrylate) on the pore surface of the monoliths. Finally, the pendant glycidyl
groups on this grafted layer were functionalised by ring-opening reactions with
either p-hydroxyphenylboronic acid or p-(aminomethyl)phenylboronic acid,
yielding boronate extraction columns with capacities of 2.3 μmol/mL or
0.03 μmol/mL respectively. The p-hydroxyphenylboronic acid functionalised
column was stable at up to 250 bar pressure. It was interfaced to an electrospray
ionization mass spectrometer where its selectivity was demonstrated by separation
of glycated and non-glycated peptides. The broad diol selectivity of the material
was further demonstrated by extraction of 11 nucleosides and by extraction of
guanosine from a spiked urine sample.
The second body of work deals with the conception and development of a new
approach to controlling eluent composition gradients in chromatography.
Gradient liquid chromatography typically relies on systems with multiple pumps
that mix stock solutions at varied ratios or systems with electrolytic eluent
generation. This thesis introduces an entirely new method in which a
photosensitive chemical is dissolved in the eluent and irradiated at variable intensities as it is pumped through a photoreaction tube to create isocratic or
gradient eluent profiles. Six different acid-generating photochemical reagents
were tested and it was found that 2-chloro-1-(2,5-dimethyphenyl)ethanone was
the most suitable chemical for generating acid concentration gradients. The
system was demonstrated for capillary scale inorganic cation exchange
chromatography with suppressed conductivity detection and pH gradient reversed
phase chromatography with on-line mass spectrometry detection. The advantages
of this photochemical approach to eluent generation, including greater solvent
compatibility than electrochemical methods and greater design simplicity for
simpler miniaturised chromatography systems, are discussed.
|Item Type:||Thesis (PhD)|
|Keywords:||liquid chromatograhpy, affinity chromatography, polymer, monolith, photochemistry, mass spectrometry|
Copyright © the Author
|Date Deposited:||12 Dec 2011 22:35|
|Last Modified:||11 Mar 2016 05:53|
|Item Statistics:||View statistics for this item|
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