The introduction of supercritical CO₂ at packed column supercritical fluid chromatography (SFC) flow rates is shown to significantly affect the excitation characteristics of a helium microwave induced plasma (He MIP). In this work, the influence of CO₂ on specific atomic and ionic transitions of Cl, Br, I, P, and S is described. Also presented is the determined relationship between transition energy and degree of signal depression resulting from the introduction of CO₂ to the plasma. Attempts to enhance the emission signals of non-metals by introducing H₂ into a He MIP are discussed. The inadequacy of excitation temperature, ionization temperature, rotational temperature, and electron number density measurements to determine the effect of CO₂ on the excitation characteristics of a He MIP is also described. However, application of kinetic theory and a recently developed theory on charge transfer allows a reasonable series of mechanisms to be developed that describe the excitation processes of a He MIP to which supercritical CO₂ is added. The remainder of this work describes a direct interface between a supercritical fluid extraction (SFE) vessel and an Ar MIP for the purpose of element selective detection. The response of the plasma to the introduction of sample via SFE at a variety of extraction temperatures, pressures, and sample concentrations is presented. / Ph. D.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/39732 |
| Date | 10 October 2005 |
| Creators | Ducatte, Gerald Roger |
| Contributors | Chemistry, Long, Gary L., Anderson, Mark R., Merola, Joseph S., McNair, Harold M., Taylor, Larry T. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation, Text |
| Format | x, 105 leaves, BTD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 30760478, LD5655.V856_1993.D833.pdf |
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