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Non-targeted screening of house dust samples using accurate mass TOFMS
Citation:
Strynar, M., S. Liang, R. McMahen, AND A. Richard. Non-targeted screening of house dust samples using accurate mass TOFMS. SETAC, Vancouver, BC, CANADA, November 09 - 13, 2014.
Impact/Purpose:
The National Exposure Research Laboratory (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA mission to protect human health and the environment. HEASD research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.
Description:
House dust exists as an environmental repository of chemicals to which we are exposed in our homes. A growing number of studies have targeted select persistent organic and inorganic pollutants found in house dust. Many have concluded that dust exists as an important human exposure matrix, and additional investigations to determine the chemical content of house dust would be beneficial. To that end, a non-targeted screening approach was developed to investigate dust samples (n=56) collected as part of the American Healthy Homes Survey (AHHS). The samples were extracted with organic solvent via sonication, prepared with solid phase extraction (SPE) and analyzed via +/- liquid chromatography-time of flight mass spectrometry (LC-TOFMS). Accurate mass predictions of [M-H]-, [M+COOH]-, and [M+H]+ for each molecular formulae were determined and used as the primary ions of interest to compare against a chemical database (n=~15,000 unique compounds and includes: CAS#, chemical name, and molecular formula) from the US EPA’s National Center of Computational Toxicology (NCCT). Additionally, generated molecular features were scored based on isotope pattern matching with found formulae, and only considered if scoring was >90%. Results will be shown that summarize the chemicals found in the dust, the frequency of detection, and evidence supporting the tentative identification of these chemicals.