Date of Award
Ph.D. in Chemistry
Chemistry and Biochemistry
Randy M. Wadkins
High sensitivity, selectivity and remarkable identification capabilities facilitate the applicability of mass spectrometry (MS) in diverse fields. This dissertation outlines how this cutting edge technology is used to determine the chemical composition of the ultra-small nanomolecules (NMs) to atomic precision and obtain spatial resolution of selected biomolecules using mass spectrometry imaging (MSI). Chapter I includes introduction to electrospray ionization (ESI) and matrix assisted laser desorption ionization (MALDI) MS used in my PhD research. Chapter II explains how high resolution ESI-MS methods were developed to analyze the polar water-soluble NMs. These new methods express how ESI-MS parameters need to be optimized to analyze the polar NMs based on their polarity, chain-length of the ligands, size and stability. In addition, new methods are presented on how to overcome comissues such as impurities, adduct formation and solvent clusters arising during the analysis of polar NMs including the special approach to enhance the peak intensities and lower the fragmentations. To expand the horizons of the invented MS protocols, this chapter explains new protocols to synthesis, separation and purification to get highly monodisperse NMs in an unprecedented range from 10's to 1000's of atoms. Chapter III contains new MSI methods developed to study biologically important molecules and their spatial location in different samples such as microbial colonies, animal tissues, plant tissues and forensic samples. The microbial species produced important natural products and metabolites which can be applicable in different fields. This chapter has two themes based on method development for MSI to detect the important secondary metabolites including rapamycin and manzamine in bacteria colonies. During imaging experiments new metabolomes including iturin and fengycin were detected. After the discovery of iturin, to the new MSI method facilitated the study of how host plant regulates iturin production. Recently, most imaging applications are based on animal tissue imaging due to the pharmaceutical involvement and disease control. This chapter includes MSI method developed to detect neurotransmitters in chick brain tissues. Further, chapter III contains studies based on MSI method developed for detection of natural products in plant tissues. Finally, a MSI method was developed for detection of analytes in forensic samples.
Kothalawala, Nuwan K., "Method development for mass spectrometric characterization of ultra-small nanomolecules and mass spectrometry imaging of selected biomolecules" (2015). Electronic Theses and Dissertations. 1366.