Dissertation
Band Broadening Phenomena in Liquid Phase Ion Mobility Spectrometry
Doctor of Philosophy (PhD), Washington State University
01/2014
Handle:
https://hdl.handle.net/2376/5422
Abstract
Growing demand for mobile analytical tools to detect explosives, illicit drugs and other forensic related compounds has led to the development of several miniaturized ion mobility spectrometers, yet many have limited performance. Liquid phase ion mobility spectrometry (LPIMS) has the potential to become a highly efficient, but small separation device. However, in recent work high resolving powers have not been achieved promised by LPIMS theory. Thus, the primary focus of the research presented here was to identify the band broadening processes that has led to low resolving powers in the practice of LPIMS and to suggest methods in which the resolving power of LPIMS can be improved. Using four unique ion mobility spectrometers, which were all constructed during the process of this work, electric field inhomogeneity, ion cluster formation, gate pulse efficiency, and Coulombic repulsion were investigated as possible.. In addition to these four ions mobility spectrometers, three ion gating methods and two ionization sources were investigated. Overall, band-broadening effects of electric field inhomogeneity, ion cluster formation, and gate pulse efficiency were reduced or eliminated. Coulombic repulsion in the liquid phase was the identified as the primary band broadening problem in LPIMS. For the gas/liquid phase design, ion transport through both gas and liquid were demonstrated, but a "stacking" phenomenon was observed at the gas/liquid interface. Due to differences in ion velocities, the ion density at the interface increased ~1000 times, generating a Coulombic explosion that increased both band width and mobility. About an order of magnitude improvement in the resolving power was reported when the charge density of the gas phase portion in GPLIMS system was reduced from 1071 V/cm to 371 V/cm. In addition to decreasing the charge density at the gas/liquid interface, resolving power was increased with longer liquid drift lengths and shorter pulse widths. In GPLIMS resolving power of 20 was achieved
Metrics
8 File views/ downloads
22 Record Views
Details
- Title
- Band Broadening Phenomena in Liquid Phase Ion Mobility Spectrometry
- Creators
- Manuja Rasangi Lamabadusuriya
- Contributors
- Herbert H Hill (Advisor)William F Siems (Committee Member)Brian H Clowers (Committee Member)Samar K Guharay (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Chemistry, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 187
- Identifiers
- 99900581642301842
- Language
- English
- Resource Type
- Dissertation