Effects of additives on analyte migration behavior in capillary electrophoresis

The aim of this work is to study the effects of additives on the analyte migration behavior in capillary electrophoresis (CE). The first part of this thesis presents an investigation into the interaction between the analytes and the additives in both the liquid and gas phase. ß-Cyclodextrin (ß-CD) was used as the additive and several nitrophenols were employed as analytes to compare the trends of the binding affinity in the gas and liquid phase. It was demonstrated that the trend of the equilibrium constants (K) in the aqueous phase determined by CE was the same as in the gaseous phase determined by electrospray mass spectrometry. It was also concluded that ammonium ions were bound to (ß-CD in the gas phase. The second part of this thesis presents a quantitative study of ion-pairing interactions in CE. The ion-pairing agents dodecyltrimethylammonium bromide (DTAB) and tetramethylarnmonium bromide (TMAB) were used as additives in several separation buffers to examine the relationship between the analytes and the additives in aqueous and nonaqueous CE. It was concluded that the interaction between the analytes and the additives in this study was mainly due to ion-pairing and that hydrophobic interactions played a minor role. In the final part of this thesis, the effects of multicomponent additives were studied. Sulfobutylether-ß-CD (SBE-ß-CD) and hydroxypropyl-ß-CD (HP-PCD) were used as differently charged additives. Once the interaction between the analytes with each additive was understood, the effects of a mixture of the two differently charged additives were examined.Science, Faculty ofChemistry, Department ofGraduat