Grantee Research Project Results
Development of High-Resolution Chemical Ionization Mass Spectrometry Methods for Real-Time Measurement of Emerging Airborne Per- and Polyfluoroalkyl Substances (PFASs)
EPA Grant Number: R840431Title: Development of High-Resolution Chemical Ionization Mass Spectrometry Methods for Real-Time Measurement of Emerging Airborne Per- and Polyfluoroalkyl Substances (PFASs)
Investigators: Surratt, Jason D. , Zhang, Yue , Turpin, Barbara J , Brooks, Sarah D , Zhang, Zhenfa
Institution: University of North Carolina at Chapel Hill , Texas A & M University
EPA Project Officer: Chung, Serena
Project Period: May 1, 2022 through May 8, 2025
Project Amount: $799,833
RFA: Measurement and Monitoring Methods for Air Toxics and Contaminants of Emerging Concern in the Atmosphere (2021) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Endocrine Disruptors , Environmental Engineering , Watersheds
Objective:
>8,000 PFASs are currently known, many of which have been widely used in industrial/manufacturing processes (or byproducts thereof) due to their high stability/low degradation rates. These anthropogenic and environmentally-persistent organic chemicals used in many consumer products can cause adverse human health effects; however, their presence, abundance, and transformation in air remain highly uncertain. Thus, we aim to combine state-of-the-art online high-resolution chemical ionization time-of-flight mass spectrometers (HR-ToF-CIMS and Vocus 2R CI-ToF) together with novel air- and particle-phase sampling techniques to increase our understanding of fugitive PFAS emissions from stationary point sources. Our overarching hypothesis is that CIMS methods using iodide (I-), nitrate (NO3-), hydronium (H3O+), or nitrosyl (NO+) reagent ions can efficiently measure airborne PFASs in real-time down to parts per trillion (ppt) or sub-ppt levels, with 3 objectives addressing this: (1) Determine HR-ToF-CIMS and Vocus 2R CI-ToF calibration curves and detection limits for atmospherically-relevant PFASs by using commercially-available and synthesized standards; (2) Oxidize these PFAS standards with hydroxyl radicals (OH)/ozone (O3) in controlled laboratory settings to generate commercially-unavailable PFASs and to also gain insights into their atmospheric transformations/fates; and (3) Deploy a mobile laboratory with these newly developed/lab-validated CIMS methods and other air- and particle-phase sampling techniques at a stationary point source to study fugitive PFAS emissions and their near-source downwind chemistry.
Approach:
For high-to-semi-volatile PFASs, HR-ToF-CIMS and Vocus 2R CI-ToF will directly sample air as a function of atmospherically-relevant humidity conditions. For low-volatility PFASs that often partition to airborne particles, a Vocus Inlet for Aerosols (VIA) will be used to evaporate these before being chemically characterized up to 1 Hz time resolution without pre-concentration steps. Comparisons will be made with existing liquid/gas chromatography methods coupled to MS that traditionally measure PFASs from filters/PUF-XAD. Preliminary HR-ToF-CIMS data show ppt to sub-ppt detection for several PFASs. Oxidation flow reactors (OFRs) will react lab/field-sampled PFASs with OH/O3 in the absence/presence of ambient-like aerosols, resulting in characterized transformation products needed for source tracking. The TAMU mobile lab will deploy these newly developed methods to sample and chemically characterize fugitive emissions from a stationary source in Fayetteville, NC (Chemours).
Expected Results:
This work will provide a “new advancement in measurement techniques,” such as HR-ToF-CIMS and Vocus 2R CI-ToF/VIA methods to measure both gas- and particle-phase PFASs, in order to “achieve real-time, continuous measurements” of PFAS levels “with minimum detection limits below background concentrations.” The proposed work also brings “advancements in stationary/mobile near source measurement methods” essential to providing facility-wide PFAS emission estimates. Results from this study will help EPA achieve its mission to protect human health and the environment, especially in low-income minority/rural communities.
Publications and Presentations:
Publications have been submitted on this project: View all 14 publications for this projectJournal Articles:
Journal Articles have been submitted on this project: View all 2 journal articles for this projectSupplemental Keywords:
GenX, PFOS, PFOA, organic fluorine, environmental chemistry, analytical, measurement methods, southeast U.S., North Carolina (NC), fine particulate matter (PM2.5), atmospheric chemistry, air pollution, and EPA Region 4.Progress and Final Reports:
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.