Incorporation of Chiral Selectors into a Water Stationary Phase for use in Supercritical Fluid Chromatography
Date
2018-06-14
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Abstract
The direct separation of enantiomers in column chromatography is an important field that has seen considerable maturation and explosive growth in the last three decades. This development has been spurred by needs for fast and cost-effective analysis in application areas such as pharmaceuticals, agrochemicals, and environmental toxicology. Despite this progress, method development in chiral analysis is often difficult and prohibitively costly due to expensive columns and lack of universally applicable selectors. This thesis presents a new method for chiral separations using a modified aqueous stationary phase. By incorporating chiral selectors in a liquid phase on stainless steel capillary tubing, chiral separations may be achieved conveniently and at extremely low cost. Further, the application of unmodified carbon dioxide as a mobile phase for these separations eliminates the need for costly and potentially harmful organic solvents in routine operation, and also allows the use of the universal flame ionization detector. Toward this end, efforts to effect separations using native and derivatized beta cyclodextrin selectors were undertaken, with some promising results for the separation of some flavanone enantiomers. Especially notable was the extremely potent selectivity obtained at novel operating conditions such as subambient temperatures. The thermodynamic and kinetic performance of the system was evaluated revealing some highly novel characteristics. To enable separation of a greater diversity of chiral analytes, the macrocyclic antibiotic selector vancomycin was also investigated. Excellent performance was obtained using this selector for the separation of some phenoxypropionic acid enantiomers. The addition of additives was highly relevant to these separations. Most notably the improvement with ternary agents such as triethylamine revealed the utility of the water stationary phase as a unique molecular scaffolding for promoting chiral discrimination. Finally, applications demonstrating the separation of both a flavanone and phenoxypropionic acid in complex sample matrices, as well as mixed selector phases utilizing both beta cyclodextrin and vancomycin for the simultaneous separation of multiple chiral pairs highlighted the versatility of the novel separation system.
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Keywords
Chiral, Chromatography, Supercritical
Citation
Frantz, J. J. (2018). Incorporation of Chiral Selectors into a Water Stationary Phase for use in Supercritical Fluid Chromatography (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/32002