Date Approved

2011

Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department or School

Chemistry

Committee Member

Heather Holmes, PhD, Chair

Committee Member

Timothy Brewer, PhD

Committee Member

Gavin Edwards, PhD

Abstract

It has recently been hypothesized that gastrointestinal microbiota modulate immune response by the production of short-chain fatty acids (SCFAs). There is a need for rapid, selective analytical methodology capable of trace analysis of SCFAs in complex biological matrices. Previous studies by others using multibed-sorbent traps, solid phase microextraction (SPME), and on-fiber derivatization with SPME showed that it is possible to achieve low limits of detection (LODs) for the gas chromatographic (GC) headspace analysis of SCFAs. The goal of this project was to achieve on-trap derivatization of SCFAs by incorporating a derivatizing agent onto a sorbent trap. Preconcentration and derivatization of acetic and propionic acids by the trap prior to entering a GC column produced FID signals for low ppb level concentrations of SCFAs that were competitive with mass spectrometry detection and followed a linear trend over two orders of magnitude. PDAM (1-pyrenyldiazomethane) impregnated poly(acrylate) was monitored on a daily basis and found to be stable up to ten days at room temperature when stored in an amber vial. The most significant challenge resulted from the manual construction of sorbent traps, which can negatively impact chromatographic reproducibility due to interfence of the flow of analytes and carrier gas both into and out of the trap. Alternative trap designs are under consideration to address this issue.

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