Spelling suggestions: "subject:"mass spectrometry"" "subject:"mass spectometry""
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DEVELOPMENT OF A SYNTHETIC METHOD FOR 2-TETRAZENES AND EXAMINATION OF THE MASS SPECTROMETRIC BEHAVIOR OF IONIZED 2-TETRAZENES AND ASPHALTENE MODELHao-Ran Lei (13965753) 17 October 2022 (has links)
<p> 2-Tetrazens are often used as high energy-density materials. Only a few synthetic methods exist for making them. Further, their structure-property relationships remain largely unexplored. Asphaltenes are usually a complex mixture found in the heaviest fraction of heavy crude oil. Their structural characterization and understanding have become a pertinent task for petroleum industry around the world. Mass spectrometry is a powerful analytical tool for the detection and characterization of unknown compounds even in complex mixtures. It features high sensitivity and speed and can provide a variety of valuable information for different types of analytes. This thesis focuses on the development of an effective synthetic method for 2-tetrazenes and the mass spectrometry study of the ionized 2-tetrazenes. In addition, the mass spectrometric behavior of ionized asphaltene model compounds are also discussed in this thesis. Chapter 2 describes the instrumentation and fundamental aspects of the mass spectrometers used in the research discussed in this thesis. Chapter3 introduces an effective synthetic method for 2-tetrazens based on iodine-mediated oxidative N-N coupling reaction of hydrazines. Chapter 4 presents the fragmentation behavior of ionized 2-tetrazenes in tandem mass spectrometry experiments. Upon collision-activated dissociation (CAD), ionized alkyl-substituted linear 2- tetrazenes underwent simpler fragmentation reactions than the ionized aromatic 2-tetrazenes or a cyclic 2-tetrazene. The observations were rationalized by using quantum chemical calculations. Chapter 5 presents the fragmentation behavior of ionized asphaltene model compounds under medium-energy collision-activated dissociation (MCAD). The comparison between the different behaviors of the molecular radical cations of these compounds provided useful information for the identification of related unknown compound </p>
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TWO-DIMENSIONAL TANDEM MASS SPECTROMETRY: INSTRUMENTATION AND APPLICATIONLucas J Szalwinski (12469362) 27 April 2022 (has links)
<p>Mass spectrometry has become the premium chemical identification method. The next advancement for mass spectrometry is the widespread use of mass spectrometers for on-site chemical/biological identification. Ion trap mass spectrometers have emerged as powerful on-site analytical platforms, in spite of limited mass resolution, due to their compatibility with ambient ionization methods and ready implementation of tandem mass spectrometry (MS/MS). However, conventionally operated ion traps are inefficient in accessing the entire tandem mass spectrometry dataspace. By operating the ion trap at a constant trapping voltage, more efficient tandem mass spectrometry scan modes are accessible. The most efficient is to acquire the entire tandem mass spectrometry data space and this work demonstrates three different methods of acquiring this data domain. These methods acquire the data in under a second and the best performing method was implemented in a miniature mass spectrometer without performance decrease. The impact of this device is most powerful when analysis requires the entire ionized sample be considered to determine the identity of the sample. This was shown to be useful for monitoring the lipid metabolism in a model microorganism. </p>
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