Defense Date


Document Type


Degree Name

Master of Science


Forensic Science

First Advisor

Christopher Ehrhardt

Second Advisor

Michelle Peace

Third Advisor

Matthew Halquist

Fourth Advisor

Justin Poklis


Lipopolysaccharides (LPS) are a major component of the outer membrane in Gram-negative bacteria species and are responsible for toxicity caused by organisms such as Escherichia coli (E.coli). Conventional methods for characterizing LPS utilize mass spectrometry, particularly matrix assisted laser desorption ionization mass spectrometry (MALDI-MS) and liquid chromatography mass spectrometry (LC-MS). Although these are successful in analyzing intact LPS molecules, they can be time-consuming. Other mass spectrometry techniques, such as direct analysis in real time/time-of-flight mass spectrometry (DART-TOF-MS) could also be helpful in the rapid analysis of LPS molecules without sample extraction procedures. This research focuses on the application of a DART-TOF-MS method to rapidly identify LPS molecules from E. coli as well as an analysis of LPS extracts generated using a commercial LPS extraction kit by gas chromatography-flame ionization detection (GC-FID). It was determined that DART-TOF-MS allows for the direct detection of LPS-specific fatty acids from solutions containing intact E.coli cells. Finally, the GC-FID based evaluation of the commercial LPS extraction kit showed that resulting extracts were enriched in LPS-specific fatty acids compared to intracellular/membrane fatty acids.


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