Author ORCID Identifier
https://orcid.org/0009-0009-9795-2633
Defense Date
2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Chemistry
First Advisor
Maryanne Collinson
Abstract
Liquid Chromatography (LC) is increasingly being used for more complex samples that need to be effectively separated and quantitated. A gradient in the functionalization of the stationary phase allows for novel selectivity and better resolution compared to a uniform column. This work is focused on the improvement of the creation of these columns, the separation of difficult analytes on these columns, and adaptation of a retention simulator to study optimized dual gradient SPG shapes for the separations of large molecules.
In this work, C8 and C4 continuous stationary phase gradients were fabricated using destructive controlled rate infusion with trifluoroacetic acid. Thermogravimetric analysis along the length of the column established the gradient shape and the radial homogeneity of the stripped columns. This work has improved upon previous stationary phase gradient stripping procedures for added reliability.
The created columns were tested chromatographically for their stability, hydrophobicity and applicability to the separation of difficult analytes. To study the capabilities of the established stationary phase gradients, the C8 gradients were tested with nicotine analytes, and the C4 gradients were tested for protein and peptide separations.
Experimental chromatographic data obtained from uniform C4 testing established fitted Linear Solvent Strength model parameters. These values were then re-parameterized, improving the quality of the fit. Additionally, a strong canonic exchange column was parameterized with the same analytes to simulate an orthogonal retention mechanism. Based on these values, the effects of varied stationary phase gradient proportions were explored and optimal gradient shapes were found.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
12-12-2025