Degree
Doctor of Philosophy (PhD)
Department
Department of Chemistry
Document Type
Dissertation
Abstract
One of the most well-studied psychoactive complex matrices is the Cannabis plant. Although its marijuana variety is illegal at the federal level in the United States, it has been decriminalized in numerous state-level jurisdictions. The current forensic analytical techniques employed for the analysis of Cannabis and its derived products, such as edibles, are based on chromatographic approaches, including gas- and liquid chromatography-mass spectrometry (GC- and LC-MS). These established protocols require time-consuming and resource-intensive sample pretreatment steps in order to render a sample to a form that is suitable for the detection of targeted compounds (i.e., cannabinoids, terpenes, etc.). In recent years, the application of the ambient ionization mass spectrometry method, direct analysis in real time – high-resolution mass spectrometry (DART-HRMS), demonstrated its ability to enable rapid screening of Cannabis and products derived from it. However, there are aspects of the DART-HRMS analysis of Cannabis which are still challenging for forensic practitioners, or unexplored in the literature, which prompted the investigations described herein.
Presented in this work is the development of an approach for the comprehensive characterization of compounds found in Cannabis, as well as food and beverage products within which Cannabis-derived compounds have been infused. First, a broadly applicable protocol for the differentiation of cannabinoid isomers present within complex matrices was developed, leveraging the capabilities of DART-HRMS. Then, computational methods were used to facilitate structural identification of an entity detected by DART-HRMS analysis of Cannabis that was previously reveled by chemometric approaches to be important in enabling forensic differentiation of Cannabis varieties. Finally, the recent discovery of organosulfur compounds in Cannabis lead to a study that revealed the mechanisms by which these compounds generate novel gas phase ions during DART-HRMS analysis, which in turn led to development of a broadly applicable systematic approach for the interpretation of the DART mass spectra of organic sulfides and disulfides.
The ambient ionization mass spectrometry method addresses and circumvents current challenges for the comprehensive chemical analysis of Cannabis. The results contribute to the ever-growing field of Cannabis characterization, and facilitate the advancement of the forensic, medicinal, and nutraceutical sciences.
Date
5-14-2026
Recommended Citation
Garosi, Benedetta, "Chemical Interrogation of Complex Matrices Using Ambient Ionization Mass Spectrometry: Practical Approaches for the Identification of Small Molecules and Mechanistic Interpretation of Metastable Helium-Promoted Gas Phase Ions" (2026). LSU Doctoral Dissertations. 7086.
https://repository.lsu.edu/gradschool_dissertations/7086
Committee Chair
Musah, Rabi A.
LSU Acknowledgement
1
LSU Accessibility Acknowledgment
1
Included in
Analytical Chemistry Commons, Computational Chemistry Commons, Forensic Chemistry Commons