Application of Fourier transform ion cyclotron resonance mass spectrometry to a mechanistic study, examination of the properties of nucleobase radical cations, and chemical ionization reagent development
Abstract
Three distinct studies were carried out using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR). Chapter 3 describes the investigation of the mechanism of isomerization of the methyl propionate radical cation to a stable enol form (ΔHisomerization = −32 kcal/mol). The results of a deuterium labeling study indicate that the isomerization proceeds through two competing pathways. Chapters 5, 6, and 7 describe the determination of the adiabatic recombination energy and acidity of adenine, thymine, and 1-methylthymine radical cations. The intrinsic (solvent-free) reactivity of these nucleobase radical cations was examined also. The radical cations were found to react predominately by electron and proton transfer. A proton transfer catalyzed isomerization mechanism leading to a distonic ion is proposed as a likely explanation for the observed isomerization of thymine radical cation. Solvation calculations suggest that isomerization may also be possible within DNA provided a base catalyst is present. Chapter 8 describes the investigation of potential chemical ionization (CI) reagents for selective ionization of different molecule classes in a base oil matrix. Protonated aniline and protonated trimethyl phosphite are proposed as possible CI reagents for selective ionization of nitrogen containing species in base oil samples. The dimethylene ketene distonic ion is proposed for selective ionization of alkyl sulfur compounds.
Degree
Ph.D.
Advisors
Kenttamaa, Purdue University.
Subject Area
Analytical chemistry
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