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Theses and Dissertations

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Browsing Theses and Dissertations by Subject "aerosol"

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    ItemOpen Access
    Laboratory evaluation of a microfluidic electrochemical sensor for aerosol oxidative load
    (Colorado State University. Libraries, 2012) Shapiro, Jeffrey, author; Volckens, John, advisor; Henry, Charles, committee member; Peel, Jennifer, committee member
    Human exposure to particulate matter (PM) air pollution is associated with both human morbidity and mortality. The mechanisms by which PM impacts human health are yet unresolved, but evidence suggests that PM intake leads to cellular oxidative stress through the generation of reactive oxygen species (ROS). Therefore, reliable tools are needed for estimating the oxidant generating capacity, or oxidative load, of PM. The most widely reported method for assessing PM oxidative load is the dithiothreitol (DTT) assay. The traditional DTT assay utilizes filter-based PM collection in conjunction with laboratory analysis. However, the traditional DTT assay suffers from poor time resolution, loss of reactive species during sampling, and high limit of detection. Recently, a new DTT assay was developed by coupling a Particle Into Liquid Sampler with microfluidic-electrochemical detection. This 'on-line' system allows continuous monitoring of PM reactivity (~three minute measurement resolution) from substantially reduced sample masses (nanograms). This study reports on a laboratory evaluation of the on-line DTT approach. A standard urban dust sample was aerosolized in a laboratory test chamber at three atmospherically-relevant concentrations allowing comparison of the on-line and traditional DTT methods. The on-line system gave a stronger correlation between DTT consumption rate and PM mass (R2 = 0.93) than the traditional method (R2 = 0.29). The on-line system also reported ~1.4 times greater relative reactivity for a given PM sample compared to the traditional method (p = 0.022) indicating improved efficiency for the capture and detection of redox-active species. These results suggest that on-line methods for PM sampling and reactivity analysis may improve our ability to study impacts of PM exposure on human health.
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    ItemOpen Access
    Personal, spatiotemporal exposure assessment: method development and application
    (Colorado State University. Libraries, 2013) Adams, Colby D., author; Volckens, John, advisor; Reynolds, Stephen, committee member; Peel, Jennifer, committee member; Brazile, William, committee member; Laituri, Melinda, committee member
    To view the abstract, please see the full text of the document.