Investigating the Release of Poly- and Perfluoroalkyl Substances from AFFF-impacted Soils with LC-QToF-MS

PRESENTER: Dr Andrew Maizel (Colorado School of Mines)

ABSTRACT: Aqueous film-forming foams (AFFF) manufactured by 3M, Ansul, and National Foam have been observed to contain polyfluorinated compounds at higher concentrations than perfluorocarboxylic acids, though the reverse is typically observed in AFFF-impacted groundwaters. The loss of these, often cationic or zwitterionic, polyfluorinated compounds may derive from their preferential retention by source-zone soils. In this seminar, we present initial findings from soil column experiments that investigate the role of soil characteristics and geochemical conditions on the release of poly- and perfluoroalkyl substances (PFASs) from AFFF-impacted soils. The use of LC-QToF-MS allows a broad suite of PFASs to be identified in AFFF-impacted soils and soil column effluents. Over forty “target” PFASs are quantified by comparison with reference standards and mass-labeled surrogates. However, as reference standards are not available for many polyfluorinated compounds, hundreds of additional “suspect” compounds are identified by comparison of MS/MS fragmentation spectra against an extensive MS/MS spectral library. Where MS/MS fragmentation spectra are unavailable, additional “suspect” compounds are identified by comparison of accurate parent mass against an extracted ion chromatogram list, which contains compounds identified in literature or speculated to be present at AFFF-impacted sites. With these analytical tools, PFAS retention in soils is shown to vary according to chemical composition and soil characteristics.

PRESENTER BIO: Andrew Maizel is a postdoctoral fellow in the lab of Chris Higgins at the Colorado School of Mines. There, he studies the transport and transformation of poly- and perfluoroalkyl substances in soils impacted by aqueous film-forming foams. Previously, he obtained a doctorate at the University of Wisconsin-Madison, in the lab of Christina Remucal, where he investigated the composition and photochemistry of dissolved organic matter. He has bachelor's and master's degrees from the University of California, Berkeley and has worked as an analytical chemist at Brooks Rand Labs and the Smithsonian Environmental Research Center.