Many mass spectrometric methods, such as exact mass measurement, collision-activated dissociation and H/D exchange reactions, have been successfully used for obtaining structural information on mixture components. However, these techniques don't always allow the unambiguous identification of unknown compounds.
Gas-phase ion-molecule reactions provide a powerful tool for obtaining molecular weight, structural, functionality and chemical reactivity information for molecules, including small organic molecules, drug intermediates, synthetic polymers and petroleum components. Chapters 3, 4 and 5 in this thesis address the issue of identifying two functional groups (N-oxide and diol) present in protonated analytes. The first study (Chapter 3) involves the identification of the aromatic tertiary N-oxide functional group via ion-molecule reactions with 2-methoxypropene (MOP) in an FT-ICR. The second study (Chapter 4) describes the identification of and differentiation between protonated aromatic and aliphatic tertiary N-oxide functionalities via ion-molecule reactions with tri(dimethylamino)borane (TDMAB) followed by sustained off-resonance irradiation collision-activated dissociation (SORI-CAD). The third study (Chapter 5) focuses on the differentiation of protonated stereoisomers ( cis - and trans -diols) by using phenylboronic acid in the gas-phase.
Chapters 6, 7 and 8 focus on the analytical utility of selective chemical ionization (CI) reactions combined with laser-induced acoustic desorption (LIAD) mass spectrometry for petroleum analysis. Chapter 6 discusses the gas-phase reactions of ClMn(H 2 O) + with polar and nonpolar hydrocarbons in an FT-ICR mass spectrometer. The differentiation of isomeric hydrocarbons is also discussed in this chapter. Chapter 7 extends the applicability of LIAD/ClMn(H 2 O) + CI to the analysis of real petroleum products (base oil fractions). Chapter 8 introduces a preliminary study on molecular weight distribution of asphaltenes by LIAD/EI mass spectrometry.
