Type of Document	Dissertation
Author	Piraino, Stephanie M.
URN	etd-08192004-113511
Title	Preparing Packed Capillaries for use in Capillary Electrochromatography: Studies of Mobility, Dispersion, and Reproducibility
Degree	Doctor of Philosophy
Department	Chemistry and Biochemistry, Department of
Advisory Committee	Advisor Name Title John G. Dorsey Committee Chair Albert Stiegman Committee Member Jodee Dorsey Committee Member Thomas Vickers Committee Member
Keywords	Electrochromatography Capillaries
Date of Defense	2003-08-27
Availability	unrestricted
Abstract Packing capillaries for use in Capillary Electrochromatography (CEC) is described in detail. Qualitative observations regarding the general packing procedure are elucidated. Because forming frits to retain the stationary phase is one of the greatest challenges regarding the fabrication of packed capillaries, the performance of several types of frits including sintered frits, photopolymerized frits, and frits made by sol- gel technologies is evaluated. The frits are formed in open capillaries, and the electroosmotic mobilities are calculated and compared to those obtained in an open capillary. Run-to-run, day-to-day, and column- to-column reproducibilities are evaluated. In all cases, the run-to-run reproducibility varied by less than 4%. The greatest mobility was through the capillaries with the sol- gel frits (1.29 x 10-3 cm2/V·s) which also exhibited the best day-to-day reproducibility. The capillaries with the photopolymerized frits had the best column-tocolumn reproducibility yet the slowest mobility (1.00 x 10-3 cm2/V·s). The second central moment of benzene as a solute is calculated and plotted as a function of time to estimate the differences in peak dispersion among the various frits studied. Although the mobilities through the capillaries with the sintered frits were the most irreproducible, these frits are associated with the least amount of band broadening. As the sintered frits are the most common type of frit used for CEC, modifications to the equipment used to sinter the frits were made in an effort to make more reproducible and reliable sintered frits. The revisions made to the frit heater include the use of a transformer to vary the voltage, a nichrome ribbon to generate smaller frits, and a thermocouple to estimate the temperature while heating the capillary. The band broadening of an uncharged solute was measured as a function of sintering times and temperatures to calculate the amount of heat used to sinter the frits. It was determined that more homogeneous frits were made as more heat was applied to sinter the frit, resulting in less dispersion.
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