For a number of reasons, miniaturization of chromatographic columns has been
a general trend over the past three decades. Methods designed to enhance selectivity
and efficiency can offer improved separation power and speed, expanding on the
advantages of miniaturized columns. This dissertation describes novel approaches in
this direction, focusing on two areas: the development of affinity-type sorbents for
capillary HPLC derived from molecular imprinted polymers (MIPs) and the study of
perfusive electroosmosotic flow (EOF) and its effect on efficiency in capillary
electrochromatography (CEC).
MIPs are synthetic polymers capable of selectively binding a template
molecule incorporated prior to polymerization. MIPs prepared using nortripyline, a
tricyclic antidepressant drug, were employed to screen a simulated chemical library,
consisting of a series of structural analogs and related compounds. A parameter was
introduced to quantify the selective retention of the analytes. Library compounds
containing the major structural features of the template (ring structure and pendant 2��
amine) exhibited the highest affinity for the MIP.
The use of macroporous packings under conditions of electroosmotic perfusion
can result in improved chromatographic efficiencies. In this work, the performance of
CEC columns packed with particles having different nominal pore diameters was
investigated. The results indicate that perfusive EOF can yield significant gains in
efficiency and speed, especially when wide pore packings and dilute buffers are
employed.
A model was developed that estimates the extent of perfusive EOF expressed
as an effective particle diameter, d[subscript p,eff] The results suggest that the observed efficiency
gains are not entirely due to smaller d[subscript p,eff] values and could perhaps be due to a
decreased A term in the wide pore packings.
The electrical conductivity of CEC columns was used to assess intraparticle
flow permeability under conditions of perfusion. Results for the narrow pore (100 ��)
column were in agreement with theory for nonporous spheres, indicating intraparticle
current was negligible, while the wide pore (1000 and 4000��) columns exceeded
theoretical values by a factor of two. These results provide evidence of the existence
of "through-pores" and that intraparticle flow permeability (and potential for improved
efficiency with perfusion) is greatest with wide pore packings. / Graduation date: 2001
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/32671 |
| Date | 06 March 2001 |
| Creators | Vallano, Patrick T. |
| Contributors | Remcho, Vincent T. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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