Packing and Characterization of Capillary Columns for Ultrahigh Pressure Liquid Chromatography
Public Deposited- Last Modified
- March 19, 2019
- Creator
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Godinho, Justin
- Affiliation: College of Arts and Sciences, Department of Chemistry
- Abstract
- Improving the performance of the column remains paramount to the continued growth of ultrahigh pressure liquid chromatography. Realization of the theoretical benefits associated with sub-2 μm chromatographic supports requires homogenous packing of the sorbent into a column. This is challenging as dispersion due to transcolumn heterogeneities become increasingly important as packing material continues towards smaller particles. Although there are many studies on slurry packing, the process is highly dynamic and influenced by many interdependent parameters. The results of these studies have yielded many opinions on the “art” of column packing as opposed to the science. The experiments presented here aim to explore packing variables and associate them with column performance and the packed bed’s microstructure. Packing heterogeneities associated with slurry concentrations are identified through reconstructions of packed beds via confocal laser scanning microscopy. These heterogeneities are induced by extreme slurry concentrations. They manifest as increased local porosity and particle size segregation at low concentrations, and numerous large packing voids at high slurry concentration. It was found that an intermediate slurry concentration yields repeatable, high efficiency columns by balancing competing packing heterogeneities. These studies inspired use of high slurry concentrations and sonication to achieve highly efficient capillary columns. The resulting columns exhibit the highest ever efficiency for columns packed with porous particles with reduced plate heights of 1. These studies on the packed bed microstructure also revealed a trend in increasing interparticle porosity for columns packed with smaller particles. These trends were explored with methods to quantify the column’s total liquid volume. As instruments with increased pressure capabilities become available, longer columns can be implemented. Unfortunately, increasing a column’s length while maintaining its efficiency is difficult. In this vein, an on-column detection method to identify local column performance is described. The method allows for non-destructive measurements and may support future studies of column length as a packing variable. Although the method to pack a sorbent into a column homogeneously is important to overall efficiency, the sorbent’s particle size uniformity cannot be overlooked. A hydrodynamic chromatography method is designed and used to size refine a novel macroporous particle material.
- Date of publication
- August 2016
- Keyword
- DOI
- Resource type
- Rights statement
- In Copyright
- Advisor
- Lockett, Matthew
- Ramsey, J. Michael
- Redinbo, Matthew R.
- Dempsey, Jillian
- Jorgenson, James
- Degree
- Doctor of Philosophy
- Degree granting institution
- University of North Carolina at Chapel Hill Graduate School
- Graduation year
- 2016
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