Date of Award
Doctor of Philosophy (PhD)
R. Kenneth Marcus
Mass spectrometry has remained an important tool for chemical analysis, acting as perhaps the most information dense technique in the scientists’ toolkit. Mass spectrometry however is divided into atomic and molecular subdisciplines due to specific and distinct challenges associated with ionizing each sample type. Furthermore, molecular mass spectrometry has seen rapid developments in miniaturization leading to reduced format platforms with lower operational overhead and improved ease of use. To be clear, there are no mass spectrometry systems capable of analyzing both atomic and molecular samples, and little effort has been put forth towards developing miniaturized atomic mass spectrometry instrumentation. A bourgeoning solution to this lack of instrumentation is in the development of the liquid sampling – atmospheric pressure glow discharge (LS-APGD). The LS-APGD was initially developed for solution-based trace metal analysis and paired with optical detection systems, but has since been interfaced with a variety of mass spectrometers. Operating at atmospheric pressure, the LS-APGD has the ability to couple with any mass spectrometer having an atmospheric pressure interface, which is common for molecular mass spectrometers. As a result, the aforementioned advancements in molecular mass spectrometry are opened to atomic analysis. Furthermore, the LS-APGD demonstrated the ability to operate as a combined atomic and molecular (CAM) ionization source, the first of its kind. The LS-APGD operates using < 100 µL min-1 liquid flow and < 1 L min-1 He sheath gas, allowing for reduced operational overhead relative to many other ionization sources. Even with these unique merits behind it, there are still a variety of instrument platforms and sampling methodologies that require further development with the LS-APGD. Presented in this dissertation are efforts in coupling the LS-APGD with a diverse array of mass spectrometers, including triple quadrupole and a compact mass spectrometers, to perform CAM analyses. On these platforms, optimization is performed and analytical figures of merit are established, in addition to demonstrations of the instrument pairing capabilities. On Orbitrap mass spectrometers, the LS-APGD is used to demonstrate sampling capabilities on low polarity compounds typically exclusive to ionization sources such as atmospheric pressure photoionization (APPI). Previous efforts in U isotope ratio analysis are also investigated in an effort to further understand the effects of instrument operation on measurement variation and sources of bias.
Williams, Tyler J., "Diverse Mass Spectrometric Couplings and Applications of the Liquid Sampling–Atmospheric Pressure Glow Discharge as a Combined Atomic and Molecular Ionization Source" (2021). All Dissertations. 2792.