Date of Award

5-2010

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Chemistry

Advisor

Marcus, R. Kenneth

Committee Member

Brumaghim , Julia

Committee Member

Chumanov , George

Committee Member

Creager , Stephen

Abstract

The dietary supplement industry has expanded and many of these supplements have become an important aspect of people's everyday lives. In 1994, the U.S. Dietary Supplement Health and Education Act (DSHEA) classified numerous nutraceutical/botanical products as dietary supplements because of their beneficial medicinal properties and provided the necessary regulation to the supplement producers. Since then, the interest of the scientific community towards dietary supplements has grown intensively and numerous studies have been carried out in order to understand the chemical behavior of the active molecules in the human body. The development towards analytical methods for the quantification of the active components and adulterants in the botanical products has acquired great interest.
Presented here is the chemical characterization of botanical products via a liquid chromatography particle beam mass spectrometry (LC-PB/MS) technique with dual ionization sources (electron ionization (EI) and glow discharge (GD)). More specifically, the catechin species in green tea and the caffeic acid derivatives in echinacea extracts have been characterized. As well, an arsenic speciation study was performed for the kelp and bladderwrack extract. Validation of the LC-PB/MS system was accomplished by the analysis of the ephedrine alkaloids using ephedra-containing dietary supplement standard reference materials (SRM's) 3241 Ephedra Sinica Stapf Native Extract and 3242 Ephedra Sinica Stapf Commercial Extract from NIST. Once validated, this analytical tool was applied to the separation and characterization of green tea species in the NIST green tea SRM's which are under development. Finally, a selenium speciation method is applied to selenium enriched yeast and urine samples via LC-PB/EIMS.
Chromatographic methods (reversed-phase and ion-exchange) were developed and monitored by UV-absorbance and mass spectrometry. The GD source provides EI-like molecular fragmentation of each eluting compound. Therefore, a comparison between EI and GD sources can be carried out to contrast the mass spectra obtained. Quantification of the species is achieved by standard addition and internal standard approaches. Limits of detection in the nanogram level were obtained for the targeted species.

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