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<p>The purpose of this thesis research was to examine the gas-phase reactions of 2- methoxypropene (MOP) with protonated nitrogen-containing compounds, specifically pyridine, and aniline derivatives, in a linear quadrupole ion trap mass spectrometer. In addition, to maintain consistency with past experiments, several previously investigated sulfoxides were included in this study. The analytes were protonated via atmospheric pressure chemical ionization (APCI) in a linear quadrupole ion trap spectrometer, transferred into the ion trap, isolated, and then allowed to react with MOP inside the ion trap. </p> <p>All the protonated sulfoxides examined reacted with MOP to generate a stable adduct, as expected. They also transferred a proton to MOP. All protonated anilines reacted in the same manner with MOP. The diagnostic adduct formation reaction is proposed to involve proton transfer from the protonated analyte to MOP followed by addition of the neutral analyte to protonated MOP. In sharp contrast to sulfoxides and anilines, protonated pyridines were unreactive toward MOP. Therefore, the formation of a stable adduct is diagnostic for both sulfoxides and anilines but these compounds can be differentiated from pyridines due to the lack of reactivity of their protonated forms toward MOP. </p>

Thesis (Ph. D.)--Virginia Commonwealth University, 2007. / Prepared for: Dept. of Chemistry. Bibliography: leaf 146.

Thesis (Ph.D.)--York University, 2005. Graduate Programme in Chemistry. / Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://proquest.umi.com/pqdweb?index=0&did=1163224921&SrchMode=1&sid=7&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1195066319&clientId=5220

Kinetic data is presented for a variety of ion-neutral reactions which are relevant to the atmosphere of Titan and to the chemistry occurring in interstellar clouds. The data were recorded with a Selected Ion Flow Tube (SIFT) operating at room temperature (294 ± 4 K) and at a pressure of 0.46 Torr. Results of the recent Cassini-Huygens mission to Saturn and Titan have identified several species in the atmosphere of Titan not predicted by pre-Cassini models of the atmosphere. In order to determine the fate of three of these species (methylenimine, propionitrile and cyanodiacetylene) in Titan's ionosphere, their reactivity with the principal ions in Titan's upper ionosphere has been examined. As expected, collision rate proton transfer reactions dominate the chemistry with association channels also observed with many of the hydrocarbon ions. The results of the Cassini mission also identified several individual reactions as being of potential importance to models of Titan's atmosphere and this chemistry has also been examined. The above studies are also relevant to the interstellar medium where each of the neutral reactants have also been detected. The results of some proton transfer equilibrium studies are also presented. The gas phase basicities of propyne and acetylene have been determined to be 681 kJ mol⁻¹ and 617.4 kJ mol⁻¹ respectively. Their relative proton affinities can be estimated from these values. A combined experimental/theoretical study of the proton affinity of cyanodiacetylene (HC₅N) has enabled this value to be estimated at 770 ± 20 kJ mol⁻¹. Details of an attempt to complete the first laboratory measurement of the crucial reaction between H₃⁺ and atomic carbon are presented. The generation of atomic carbon in sufficient quantities for reaction in the SIFT was not possible with the microwave discharge source used. Other generation methods have also been explored with the laser photolysis of carbon suboxide expected to provide a possible solution to the problems encountered. The results of an investigation into the applicability of lithium ions (Li⁺) to SIFT-MS are presented. The lithium ions associated with each of the twenty-one neutral analytes examined to form pseudo-molecular ions. The association reactions were rapid (k ~ 10⁻⁹ cm³ s⁻¹) for large hydrocarbons but were much slower for smaller analytes (k < 10⁻¹¹ cm³ s⁻¹). In order to clarify some unusual experimental observations, the effect of water molecules on the observed chemistry has been examined in detail. The measured chemistry has important consequences for the applicability of Li⁺ to SIFT-MS where the presence and detection of an identifiable ion of the analyte is essential. Details of new SIFT operating software which can be run on a modern computer are given. Mass spectra and kinetic data recorded with the new software are also presented.

Kinetic data is presented for a variety of ion-neutral reactions which are relevant to the atmosphere of Titan and to the chemistry occurring in interstellar clouds. The data were recorded with a Selected Ion Flow Tube (SIFT) operating at room temperature (294 ± 4 K) and at a pressure of 0.46 Torr. Results of the recent Cassini-Huygens mission to Saturn and Titan have identified several species in the atmosphere of Titan not predicted by pre-Cassini models of the atmosphere. In order to determine the fate of three of these species (methylenimine, propionitrile and cyanodiacetylene) in Titan's ionosphere, their reactivity with the principal ions in Titan's upper ionosphere has been examined. As expected, collision rate proton transfer reactions dominate the chemistry with association channels also observed with many of the hydrocarbon ions. The results of the Cassini mission also identified several individual reactions as being of potential importance to models of Titan's atmosphere and this chemistry has also been examined. The above studies are also relevant to the interstellar medium where each of the neutral reactants have also been detected. The results of some proton transfer equilibrium studies are also presented. The gas phase basicities of propyne and acetylene have been determined to be 681 kJ mol⁻¹ and 617.4 kJ mol⁻¹ respectively. Their relative proton affinities can be estimated from these values. A combined experimental/theoretical study of the proton affinity of cyanodiacetylene (HC₅N) has enabled this value to be estimated at 770 ± 20 kJ mol⁻¹. Details of an attempt to complete the first laboratory measurement of the crucial reaction between H₃⁺ and atomic carbon are presented. The generation of atomic carbon in sufficient quantities for reaction in the SIFT was not possible with the microwave discharge source used. Other generation methods have also been explored with the laser photolysis of carbon suboxide expected to provide a possible solution to the problems encountered. The results of an investigation into the applicability of lithium ions (Li⁺) to SIFT-MS are presented. The lithium ions associated with each of the twenty-one neutral analytes examined to form pseudo-molecular ions. The association reactions were rapid (k ~ 10⁻⁹ cm³ s⁻¹) for large hydrocarbons but were much slower for smaller analytes (k < 10⁻¹¹ cm³ s⁻¹). In order to clarify some unusual experimental observations, the effect of water molecules on the observed chemistry has been examined in detail. The measured chemistry has important consequences for the applicability of Li⁺ to SIFT-MS where the presence and detection of an identifiable ion of the analyte is essential. Details of new SIFT operating software which can be run on a modern computer are given. Mass spectra and kinetic data recorded with the new software are also presented.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 489-516).

This thesis describes research that has been carried out during the years 2009-2013 as a part of my PhD project related to the method of selected ion flow tube mass spectrometry (SIFT-MS) and its application in interdisciplinary areas of research. SIFT-MS is a method that allows accurate quantification of trace gases and vapours presented in humid air with the focus on human breath; without any sample preparation and in real time. The thesis is divided into several parts. The first part reviews the history of mass spectrometry as a background for the quantitative analytical methods as PTR-MS and SIFT-MS. The second part discusses the detailed history of development of SIFT-MS, starting from principles of selected ion flow tube (SIFT) technique that has been used for study of ion-molecule reactions in the gas phase and forms the basis of SIFT-MS. The next part discusses volatile organic compounds of different biological origin: bacterial, plant and human breath metabolites that can be analyzed in real time using SIFT-MS. The main part "Results and Discussion" is divided into several subsections that serve as commentaries to the enclosed research papers published in peer reviewed journals. The first is a detailed step by step overview of the kinetics of ion molecule reactions which is the basis of...

The typical strategy for atmospheric analysis of volatile organic compounds (VOCs), is to collect discrete samples which are then transported to a laboratory for analysis. This method has limited spatial and temporal resolution, and can be both costly and time consuming. To overcome these limitations, a mobile monitoring platform was developed for real-time quantitative chemical analysis. This work describes the development of membrane introduction mass spectrometer and identi es the necessary requirements to make a reliable and e ective instrument for in-situ chemical analysis. These include, the integration of a membrane interface with a miniaturized mass spectrometer, development of a data management strategy, reducing the e ects of isobaric interferences and employing an internal standard for quantitative measurements. Furthermore, the negative e ects of environmental variables, such as the Earth's magnetic eld, were examined and e ectively eliminated. In addition, this work demonstrates quantitative mapping of atmospheric VOCs in real-time, which allows rapid identi cation of chemical plumes and therefore, areas of potential concern. Both lab and eld-based comparisons of iv membrane introduction mass spectrometer data and traditional whole air sampling canister data were undertaken. The primary eld site was near Ft. McMurray, AB where baseline data was collected around a steam assisted gravity drainage (SAGD) facility and surrounding public roads. Monitoring for fugitive emissions at this facility and surrounding bitumen mining and processing operations is demonstrated. Field data were also obtained, near an industrial site in Ft.Saskatchewan, AB, that demonstrate the e cacy of an adaptive sampling strategy. Finally, chemical ionization was investigated as a soft ionization strategy to improve chemical selectivity for the analysis of complex hydrocarbon mixtures. The development of an in-line liquid chemical ionization reagent delivery system is presented and proposed as an e ective strategy for eliminating interferences arising from biogenic terpenes and alkyl aromatics. In all, this thesis presents the design and implementation of a mobile membrane introduction mass spectrometer for atmospheric chemical analysis. Results that improve performance and demonstrate the novelty of the data-type are provided, along with avenues for future development. / Graduate / 0486 / 0799 / 0608

<p>Mass spectrometry (MS) alone or coupled with high-performance liquid chromatography (HPLC) or gas chromatography (GC) is a versatile analytical tool that is routinely employed for identification of unknown compounds in complex mixtures. MS operates by separating ionized analytes based on their mass-to-charge (<i>m/z</i>) ratios. If the analyte can be ionized without complete fragmentation, MS provides molecular weight information and, if performed at high resolution, elemental compositions for the ionized analytes. Tandem mass spectrometry (MSⁿ, n <u>></u> 2 where each MS step corresponds to an ion isolation or separation event) also provides structural information of ionized analytes. With this approach, structural information of the ionized analytes is obtained by isolating the ionized analytes of interest and subjecting them to fragmentation experiments, such as collision-activated dissociation (CAD). The ions of interest can also be isolated and allowed to react with gaseous molecules to generate product ions (ion-molecule reactions). </p> The experiments described in this dissertation focused on the development of tandem mass spectrometry methods based on CAD and/or gas-phase ion-molecule reactions for the differentiation of acyl, <i>N</i>- and <i>O</i>-glucuronide drug metabolites and for identification of primary carbamates as potentially mutagenic impurities. Further, by using a previously published method titled Distillation, Precipitation, Fractionation Mass Spectrometry (DPF MS), the chemical compositions of five crude oil samples, including heavy, medium, and light crude oils with different API gravities, were determined. Additionally, the gravimetric percentages of different compound classes found in these crude oils are reported as well as the correlations found between API gravities and the chemical compositions of crude oils.