Supervisor: Associate Professor Koit Herodes, Institute of Chemistry
Opponent: Dr. Serge Marc Tancrède Rudaz, PhD, The Faculty of Sciences, University of Geneva, Switzerland
Summary of the thesis:
Reversed phase chromatographyc methods for analysis of pharmaceuticals (as mainly basic compounds) have used acidic conditions where analytes are predominantly on their protonated (hydrophilic) form and therefore have poor retention on stationary phase. Basic conditions for analysis of basic compounds is more suitable. For detection, often mass spectrometry is used where volatile buffer solutions are required. Selection of volatile alkaline buffer compounds is limited for liquid chromatography-mass spectrometry (LC-MS) and therefore enhancements in the selection is more than welcomed. Two fluoroalcohols - 1,1,1,3,3,3-hexafluoro-2-propanol (pKa=9.3) and 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol (pKa=9.6) have been studied and evaluated in usage as LC-MS basic buffer components.
As a result of present work the retention mechanisms provided by fluoroalcohols have described, the influence of fluoroalcohols for the ionization of analyte have been described, comparison with retention in fluorinated stationary phase have been demonstrated and advantages for usage of fluorinated alcohols as LC-MS buffer components have been demonstrated. Comparing with known buffer components fluoroalcohols provide alternative retention mechanisms and therefore the chromatographic separation can be enhanced.
Successful application of usage of fluorinated alcohols have been demonstrated for analysis of pharmaceuticals in environmental samples and human blood plasma and urine.