Thesis
Sample dehumidification to enhance formaldehyde detection by a proton transfer reaction mass spectrometer
Washington State University
Master of Science (MS), Washington State University
2009
Handle:
https://hdl.handle.net/2376/102737
Abstract
A custom built inline sample dehumidifier was connected to a Proton Transfer Reaction - Mass Spectrometer to increase the sensitivity of the PTR-MS to formaldehyde. With the dehumidifier in place, water vapor in the sample line was controlled to a dew point as low as -50 °C resulting in increased sensitivity of the PTRMS to formaldehyde and near removal of water vapor dependent sensitivity of several measureable volatile organic compounds (VOC's), including formaldehyde. Through laboratory testing of the dehumidifier, the optimal operating tube temperature and flow through the tube were determined to be -30 °C and ~ 250 sccm respectfully. At a drift tube field intensity of 120 Td and a drift tube pressure of 2.4 mbar, the normalized sensitivity of the PTR-MS to formaldehyde increased from 8 ncps/ppbV at a dew point of ~11 °C to 35 ncps/ppbV at a dew point of -30 °C. The dehumidifier was implemented during field measurements of formaldehyde during the 2009 SHARP campaign at the University of Houston. Formaldehyde concentrations show diurnal variation and intermittent pollution episodes. The mean mixing ratio for the measurement period was ~2ppbV with peaks as high as ~ 12 ppbV. The detection limit for formaldehyde implementing the dehumidifier was 244 pptV and 105 pptV at a drift tube field intensity of 120 and 80 Td, respectively.
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Details
- Title
- Sample dehumidification to enhance formaldehyde detection by a proton transfer reaction mass spectrometer
- Creators
- Jacob K. McCoskey
- Contributors
- Bertram Thomas Jobson (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525123201842
- Language
- English
- Resource Type
- Thesis