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Kinetic performance potential of different column formats and separation modes for liquid chromatography

thesis
posted on 2023-05-26, 00:59 authored by Causon, TJ
This thesis deals with theoretical and experimental studies on optimisation of separation systems performed using liquid chromatography. The two major themes of work were improving the quality of separations by maximising efficiency with respect to the analysis time (kinetic performance) and by using temperature as an experimental variable. These themes were explored for a range of separation modes and column formats utilised in liquid chromatography. Included in this thesis is a review of the principles and practices of kinetic performance optimisation for liquid chromatography. Detailed concepts covered in this thesis are introduced and future directions for chromatographic supports discussed. The role of elevated temperatures (up to 160¬¨‚àûC) for practical and performance benefits for organic polymer monolithic stationary phases is examined for typical biomolecule applications. Temperature variation, particularly rapid temperature pulsing, during the separation process is examined using ion-exchange and hydrophilic interaction liquid chromatography modes with capillary columns and a resistively heated column module. The current performance limitations for the analysis of small anions by ion-exchange chromatography are explored. Additional in silico data are used to transform experimental isocratic data to gradient performance predictions for any normalised ramp rate and physicochemical conditions. Examples of high efficiency (25,000-40,000 theoretical plates) and sample peak capacity (n\\(_c\\) = 84) were realised and closely matched predicted values. A theoretical study of the open tubular column format for liquid chromatography with a thick, porous layer of stationary phase shows the potential of this column format to improve chromatographic performance with a trade-off for mass loadability. It can be shown that total column diameters should be less than 6 ˜í¬¿m with column lengths typically greater than 0.8 m for N values in the range of 125,000‚Äö-500,000 at a maximum pressure of 400 bar. Elevated temperature LC (90¬¨‚àûC) is also shown to increase the allowable total column diameter to up to 9 ˜í¬¿m for a larger range of N values (100,000‚Äö-880,000).

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Copyright 2012 the author The main texts are published articles that cannot be made available from this repository. This record contains links to the articles at the publishers' websites.

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