
Dr. Marzieh Shojaei earned her Ph.D. from Texas Tech University, where her research focused on the characterization and treatment of per- and polyfluoroalkyl substances (PFAS) in aqueous film-forming foam (AFFF)-impacted media. In 2022, she joined Dr. Lee Ferguson’s research group at Duke University as a postdoctoral research associate. She currently serves as a Research Scientist in Dr. Ferguson’s lab, where her research centers on the characterization of fluorochemicals in lithium-ion batteries, textiles, AFFF formulations, and AFFF-impacted groundwater.
This meeting will occur on Wednesday, July 15th, from 12 pm – 1 pm EST. Please reach out if you did not receive the link through the newsletter and would like to attend.
Talk Title: “Deep characterization of per- and polyfluoroalkyl substances in current and legacy aqueous film-forming foams“
Abstract: Per and polyfluoroalkyl substances (PFAS) have been used in aqueous film-forming foam (AFFF) since the 1960s. Application of AFFFs in fire training and emergency response sites is one of the primary sources of PFAS contamination to soil and groundwater. Studies have identified hundreds of PFAS in AFFF using high resolution mass spectrometry (HRMS), but a significant fraction of organofluorine in these formulations remains uncharacterized. Characterization of AFFF formulations is crucial for understanding fate, transport, and mass-balance of PFAS in AFFF-impacted environments. Herein, targeted analysis, total oxidizable precursor assay (TOP), and non-targeted analysis were used to characterize PFAS in 170 AFFFs collected from active fire stations in North Carolina, United States. Samples were diluted 1000-10,000,000-fold in 50:50 methanol:water and analyzed for targeted and non-targeted analysis using High-Performance Liquid Chromatography (HPLC)- Orbitrap Astral mass spectrometry in ESI negative and positive polarity, with a combined data-dependent and parallel-reaction-monitoring MS/MS workflow. TOP assay was used to provide an estimate of total PFAS precursors in each AFFF. Prioritization of PFAS for structure annotation was achieved through application of newly-developed and existing informatic approaches including in silico MS/MS libraries, mass defect and fluorine:carbon ratio analysis, and diagnostic fragment and neutral loss analysis. Application of target analysis and TOP assay resulted in quantification of up to 22,200 mg/L PFAS in AFFFs. Further characterization of AFFFs using total organic fluorine showed that TOP analyses was a robust approach for closing organofluorine mass balance in AFFFs. Non-target analysis identified more than 50 suspect PFAS classes and 15 newly annotated PFAS classes in AFFF. Bis-perfluoroalkanesulfonimides (bis-FASIs) were identified in all electrochemically synthesized AFFFs, and chromatographically separated bis-FASI isomers revealed positional substitution within C6-C14 of this novel compound class. Our results will facilitate more confident annotation of PFAS in future studies and contribute to an overall understanding of PFAS releases when products such as AFFF are used.



