Master of Science (M.Sc.)
Rachel E O'Brien
Christopher J Abelt
John C Poutsma
Atmospheric chemistry has primarily focused on outdoor environments for many decades. Plenty of models based on the findings of outdoor atmospheric researchers have been built to deepen the understanding of outdoor environments and predict how certain changes in specific parameters may affect the overall atmosphere. The same cannot be said for indoor environments, which remain relatively unknown despite the fact that humans in developed countries spend the vast majority of their lives in indoor environments. This thesis seeks to provide an early look at the makeup of indoor surface films, specifically at their molecular compositions and thicknesses. These characteristics are important for understanding how surface films, a major route of human exposure to compounds which can negatively affect health, begin to form and how they evolve over time with exposure to other indoor species. Two types of surface films were analyzed in this thesis: lab-created surface films of commercial household cleaners sprayed onto glass plates, and “real-world” surface films extracted from areas of a high-traffic lecture hall on a college campus. Samples were extracted with an Indoor Surface Extractor (ISE) and analyzed with quadrupole ion trap mass spectrometry (MS), Orbitrap MS, and/or Fourier-transform ion cyclotron resonance MS. Resulting mass spectra were used to identify individual components observed in the surface films. Both listed ingredients in the household cleaners and compounds not listed as ingredients were observed in their surface film extracts’ mass spectra; quaternary amine compounds (QACs) were observed in many of the real-world surface film extract mass spectra, likely present from increasing COVID-19 sanitary measures. In a second part of this thesis, quantification of organic material in surface films was executed with aerosol MS. Citric acid was used as a proxy for the organic surface film matrix in order to build calibration curves for the response of organic material relative to two different internal standards. These calibrations were then applied to some of the same surface film extracts analyzed by qualitative MS methods to estimate the thicknesses of the films that were extracted; the results fell in line with previously published estimates of indoor surface film thickness, indicating that the experimental parameters being used are in the correct general range and can be fine-tuned for future quantification studies.
© The Author
Legaard, Emily Nicole, "Characterization Of Indoor Surface Films By High-Resolution Mass Spectrometry" (2022). Dissertations, Theses, and Masters Projects. William & Mary. Paper 1673281635.
Available for download on Monday, August 26, 2024