Ultrahigh-Resolution Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry for Fingerprinting, Source Tracking, and Allocation of Per- and Polyfluoroalkyl Substances (PFASs)
Dr. Jens Blotevogel | Colorado State University
The widespread use of aqueous film-forming foam (AFFF) for hydrocarbon fuel firefighting has created an environmental legacy for the U.S. Department of Defense (DoD) as per- and polyfluoroalkyl substances (PFAS) continue to cause sustained groundwater plume development. PFAS have also been widely used in industrial and consumer products for heat, oil and water resistance, and PFAS leaching from landfills, wastewater treatment plants (WWTPs) and other sources may lead to co-located plume development. The overarching objective of this proof-of-concept project is to apply ultrahigh-resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) to identify compounds in AFFF at the molecular level that can be used to guide the development of novel analytical approaches to identify unique marker compounds for AFFF “fingerprinting” and PFAS source allocation, and catalogue PFAS associated with AFFF releases.
A target DoD site will be identified that contains both PFAS contamination from different AFFF sources, in addition to original AFFF product(s) and frequency-of-use profiles. A potential candidate site is the Naval Air Station in Jacksonville, FL. Then, legacy AFFF samples and various industrial and consumer product samples (e.g., plating bath mist suppressants, carpet, clothing) will be collected and extracts will be produced for subsequent FT-ICR MS analysis. A computational code will be developed to assign elemental compositions for fluorinated compounds, and statistical metrics and data reduction techniques will “fingerprint” AFFF compounds and identify product-specific marker compounds. Molecular signatures will then be compared to groundwater samples to validate plume dating, source tracking and allocation. Finally, a mass spectral library and molecular catalogue for PFASs and other AFFF components based on ultrahigh-resolution mass spectra will be built and disseminated.
FT-ICR MS achieves the highest mass resolving power and mass accuracy, far surpassing QToF and Orbitrap mass spectrometry systems, sufficient to identify and resolve PFAS without prior chromatographic separation. Consequently, FT-ICR MS can reveal complex AFFF composition and identify potential biotic/abiotic degradation pathways and retardation processes fundamental to accurate assessment of the extent and long-term impact of PFAS contamination. The mass spectral library for PFAS will identify compounds at the level of elemental composition assignment, and will provide critical guidance to DoD remedial program managers to (1) track transformation and retardation processes of AFFFs temporally, (2) date plumes, (3) understand the extent of PFAS contamination, and (4) ultimately determine the potential liability associated with past releases. (Projected Completion Date February 2021)