Development and characterization of a low power helium microwave induced plasma for spectrometric determinations of metals and nonmetals

This dissertation centers on the development of a new helium microwave induced plasma. The analytical utility of this new plasma source is critically evaluated. To sustain the helium plasma a TM ₀₁₀ high efficiency microwave induced plasma, HEMIP, was used. The HEMIP is a modification of the original Beenakker cavity that precludes the use of external matching devices, such as the highly popular double tuning stub. The He-HEMIP was analytically characterized as an atomization source for metals and nonmetals with the use of atomic emission spectrometry (AES) and atomic fluorescence spectrometry (AFS). A torodial plasma was sustained in the cavity solely by the helium gas output of the nebulizer. Aqueous samples from a pneumatic glass nebulizer/Scott spray chamber were aspirated into the cavity without a desolvation apparatus. With AES, detection limits for metals and nonmetals were in the sub-ppm range. with AFS, detection limits for metals were determined to be in the low ppm to sub-ppb range and were found to be not statistically different from those reported for HCL-ICP-AFS. Linear ranges for AES and AFS ranged from four up to five and one-half orders of concentrative magnitude. The effect of sample uptake rate on the emission intensity was investigated. Ionization interferences were determined to be minimal and phosphate interferences were found not to occur. Development and characterization also included studies of the He-HEMIP's physical characteristics. Excitation and ionization temperatures were found to be approximately equal, suggesting that the He—HEMIP approaches local thermodynamic equilibrium. Evaluation of the He—HEMIP as a routine detector for sulfur during coal pyrolysis and coal extracted samples was investigated. Results showed that the He-HEMIP is selective and sensitive. Detection values compared favorably to those of certified coal samples.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Chemistry

Department dc:contributor.department

Chemistry

Grantor dc:publisher

Virginia Polytechnic Institute and State University

Year dc:date.issued

1989

Author dc:creator

• Perkins, Larry D.

Chair dc:contributor.committeechair

• Long, Gary L.

Committee members dc:contributor.committeemember

• Mason, John G.
• McNair, Harold M.
• Taylor, Larry T.
• Yoon, Roe-Hoan

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10919/54261

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/54261