published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available in print.

Thesis (Ph. D.)--Carleton University, 2000. / Also available in electronic format on the Internet.

Ion mobility spectroscopy (IMS) has been showen to provide fast on-site analysis of coarse sandy soil for the determination of polychlorinated biphenyls (PCBs). However the presence of humus results in instrument foaling and extensive down time do to instrument clean-up. For this reason a method was investigated for the ultrasonic extraction of PCBs from humus-rich soil that could be used at remote locations. Analysis of the extracted PCBs was conducted using 1) IMS and 2) gas chromatogram equipped with a dry electolytic conductiviy detector (GC/DELCD). The research conducted for this thesis outlines the method development and analysis of PCBS using these two instruments. The IMS analyiss was found to be complicated by co-extracted matrix compounds. Results and limitations of IMS analysisare present here. The method development and validation of a method for the ultrasonic extraction and analysis of PCBs using the GC/DELCD is provided.

Ion mobility spectroscopy (IMS) has been showen to provide fast on-site analysis of coarse sandy soil for the determination of polychlorinated biphenyls (PCBs). However the presence of humus results in instrument foaling and extensive down time do to instrument clean-up. For this reason a method was investigated for the ultrasonic extraction of PCBs from humus-rich soil that could be used at remote locations. Analysis of the extracted PCBs was conducted using 1) IMS and 2) gas chromatogram equipped with a dry electolytic conductiviy detector (GC/DELCD). The research conducted for this thesis outlines the method development and analysis of PCBS using these two instruments. The IMS analyiss was found to be complicated by co-extracted matrix compounds. Results and limitations of IMS analysisare present here. The method development and validation of a method for the ultrasonic extraction and analysis of PCBs using the GC/DELCD is provided.

Drift time ion mobility spectrometry (DTIMS) is a rapid post ionization gas-phase separation technique that distinguishes between compounds based on their differences in reduced mass, charge and collisional cross-section while under a weak, time-invariant electric field. Standalone DTIMS is currently employed throughout the world for the detection of explosives, drugs and chemical-warfare agents. The coupling of IMS to MS (IM-MS) has enabled the performance of time-nested multidimensional separations with high sample throughput and enhanced peak capacity, allowing for the separation of ions not only based on their mass/charge (m/z) ratios, but also their shape. This allows for the elucidation of valuable structural information that can be utilized for determining gas phase ion conformation and differentiation between closely related ionic species. Over the past decade, these advances have transformed IM-MS applications and instrumental designs into one of the most rapidly growing areas of mass spectrometry. The work presented in this thesis is aimed at the development and subsequent characterization of a novel high-resolution resistive-glass atmospheric pressure DTIMS, and the application of this prototype DTIMS to the detection of environmentally relevant compounds. A review of the different types of ion mobility spectrometers, their principles of operation, and the advantages and disadvantages of each type are presented in Chapter 1. Chapter 2 describes the design and development of our prototype resistive glass DTIMS. A detailed description of the IMS hardware, including the ion sources, custom-built control computer, pulsing electronics, data acquisition system, and the timing schemes developed to operate the instrument in standalone DTIMS, multiplexed DTIMS, and IM-MS mode, are presented. Chapter 3 presents an initial characterization of the performance of a prototype resistive glass DTIMS under a wide range of instrumental parameters and also characterizes the radial ion distribution of the ions in the drift region of the spectrometer. Chapter 4 addresses the lack of sensitivity in DTIMS and explores ion trapping and multiplexing methods, introduces the principles of multiplexing and describes an extended multiplexing approach that encompasses arbitrary binary ion injection waveforms with variable duty cycles. Chapter 5 presents a detailed theoretical and experimental study of the separation power of our DTIMS and presents an evaluation of the field homogeneity and the performance of the ion gate.

Thesis (Ph.D.)--Ohio University, November, 2004. / Includes bibliographical references (p. 168-177)

Thesis (Ph.D.)--Ohio University, November, 2004. / Title from PDF t.p. Includes bibliographical references (p. 168-177)

Preparative mass spectrometry is an important method for the synthesis of new materials. Recently, soft landing mass spectrometry has been used to land ions on surfaces to coat or otherwise alter them. Commercial soft landing instruments do not yet exist, and the physical phenomenon of soft landing has not yet been fully described. For future ion mobility soft landing research, the theory of ion mobility, ion optics and soft landing is discussed, and 2 soft landing instruments have been built and described, along with proof of concept experiments for both instruments. Simulations of the process of ion mobility and ion optics for use in these instruments, as well as some preliminary results for the optics are included. Surfaces described include copper on mica and iron on silicon. Self assembly of soft landed ions is observed on the surfaces. The instruments constructed will be useful for future soft landing research, and soft landing can be used for future materials research with special attention focused on the self-assembly of the landed ions.

Thesis (Ph.D.)--Ohio University, March, 2005. / Includes bibliographical references (p. 163-176)