Type of Document Dissertation Author Khaled, Maha Yehia URN etd-06062008-164943 Title Selectivity and detection in capillary electrophoresis Degree PhD Department Chemistry Advisory Committee
Advisor Name Title McNair, Harold M. Committee Chair Anderson, Mark R. Committee Member Castagnoli, Neal Jr. Committee Member Dessy, Raymond E. Committee Member Mason, John G. Committee Member Merola, Joseph S. Committee Member Keywords
- Capillary electrophoresis
Date of Defense 1994-08-05 Availability restricted Abstract
This work is a contribution to the minimization of some of the selectivity and detection limitations in capillary electrophoresis. A more practical design of an electrochemical detector is introduced with simultaneous on-line UV detection (1), for the selective detection of a number of pungent and neurological compounds, the piperines and the capsacinoids. Commercially available microelectrodes together with large 25 μm id fused silica capillary columns are used for the first time in the presence of an auxiliary electrode. Minimum detectable quantities and efficiencies are sample dependent and were found to be comparable to the earlier more laborious electrochemical cell designs.
To exploit the benefits of common additives that enhance the selectivity of electrolyte systems, various additives including α, β and γ Cyclodextrins, organic modifiers, as well as a series of cationic surfactants are explored for the separation of a number of industrially important isomeric aromatic carboXylic acids (2). The separation was found to depend largely on the analyte1s geometry, degree of ionization as well as on the buffer pH and composition. The resultant separations were compared for best efficiency, resolution and ruggedness.
In addition, to add to the arsenal of CE selectors, a number of new micellar systems are investigated. Oligomeric sodium 10-undecylenate, a recently introduced oligomeric surfactant (3) is structurally investigated through the separation of vitamins and the resultant selectivity and resolution is compared to the more commonly used surfactant sodium dodecyl sulfate (4). Additionally, a number of phospholipids and Iysophospholipids, common constituents of cell membranes, are investigated not only as possible MECC surfactants but also as highly hydrophobic analytes needing themselves separation (5).
Finally, as a contribution to methods development, the effect of variations in systemparameter conditions is examined in a successful separation of a number of enzymes.
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