Doctor of Philosophy (PhD)
The goal of the research presented in this dissertation is to develop effective analytical methods for the separation of both achiral and chiral analytes using polymeric surfactants. Three analytical techniques are employed to accomplish this objective: open-tubular capillary electrochromatography (OT-CEC), open-tubular capillary electrochromatography coupled to mass spectrometry (OT-CEC/MS), and micellar affinity gradient focusing (MAGF). This research work presents novel application of polymeric surfactants that contributes to improved separations of difficult to separate analytes. The first part focuses on the application of an achiral polyelectrolyte multilayer (PEM) coating using OT-CEC. The PEM coating consisting of the cationic polymer poly (diallyldimethylammonium chloride), PDADMAC, and the anionic polymeric surfactant poly (sodium undecenyl sulfate), poly-SUS, is constructed on the surface of the silica capillary wall. The performance of the PEM coating is evaluated by use of electrochromatographic experiments and shows good selectivity for both phenols and benzodiazepines. Reproducibility of the PEM coating is evaluated by computing the relative standard deviation (RSD) of the electroosmotic flow. The second part focuses on the use of a chiral PEM for OT-CEC separations. In this study, the cationic polymer consists of poly-L-lysine hydrobromide, while the anionic polymeric surfactant consists of poly (sodium N-undecenyl-L-leucine alanate). Optimal separation conditions of various chiral analytes are achieved by varying temperature and voltage as well as the number of bilayers and salt concentration used to construct the PEM coating. In the third part, the coupling of an achiral PEM coated capillary to mass spectrometry using OT-CEC/MS is investigated. The PEM coating, which consists of a single bilayer of PDADMAC and poly-SUS, is used for the separation of â-blocker and benzodiazepine analytes. Optimal separation parameters are achieved by varying the background electrolyte pH and applied voltage. Finally, the application of poly-SUS for the simultaneous concentration and separation of coumarin dyes using MAGF is investigated. The separation and focusing of coumarin dyes is enhanced by the addition of poly-SUS into the running buffer that creates a retention gradient. The effect of varying focusing times and input concentrations on peak intensity is examined.
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Kamande, Mary Waithira, "Analytical separations using polymetric surfactants" (2005). LSU Doctoral Dissertations. 3556.