Theme: 07. Per- and Polyfluorinated Alkyl Substances (PFAS)

Topic Area: 7a. Advances in the Analysis of Non-Target Per- and Polyfluorinated Alkyl Substances (PFAS)

Formatted Title:

Rapid Screening of PFAS in Real-World Water Samples Using Particle-Induced Gamma-Ray Emission Spectroscopy

Background/Objectives:

As an emerging contaminant, per- and polyfluoroalkyl substances (PFAS) have received increasing concerns and attention from both the scientific community and society. PFAS represent a class of over 12,000 man-made chemicals that have been in use since the 1940s. They have found widespread applications in various industrial and commercial products. Due to their widespread use, high water solubility, and extreme persistence, PFAS are ubiquitous in the environment and are found in most surface and groundwater resources today. They infiltrate the water system mainly through manufacturing processes, waste disposal, landfill leachate, as well as the utilization of aqueous film-forming foams in firefighting and biosolids in agricultural cultivation. Numerous studies have found that PFAS are associated with adverse human health effects in many contaminated areas. Consequently, PFAS has emerged as a significant global threat to drinking water supplies.

The conventional analytical method for PFAS analysis relies on liquid chromatography tandem mass spectrometry (LC-MS/MS). While this method offers the advantage of precise and selective analysis of specific PFAS compounds, it has limited target analyte coverage typically. Furthermore, this method often requires comprehensive sample preparation and extensive analysis time, making it both time-consuming and financially demanding.

Approach/Activities:

To quickly screen for the presence of PFAS, we used a graphitized activated carbon felt as a fast and low-cost solid-phase extraction (SPE) method to preconcentrate and capture PFAS from 1-gallon water samples in situ. These SPE felts were dried and returned to University of Notre Dame, where we applied particle-induced gamma-ray emission (PIGE) spectroscopy to determine and rapidly screen samples for the level of total adsorbable organic fluorine (AOF).

Considering the real-world water samples could be treated with inorganic fluoride, we developed a methanol rinse method to distinguish the total fluorine signals between inorganic fluoride and organic fluorine. Recent studies have discovered the prevalence of ultrashort-chain PFAS in drinking water systems, with approximately 98% of PFAS detected in water samples being ultrashort-chain PFAS. Thus, we introduced an acid rinse method aimed at removing inorganic fluoride and ultrashort-chain PFAS from longer-chain PFAS from water samples that are adsorbed to the GAC felt.

The combined approach of SPE, methanol rinse method, acid rinse method, and PIGE analysis were applied to northern Indiana drinking water and surface water samples. These samples were collected from public water resources, as well as rivers and creeks from various locations, and were subsequently analyzed in our laboratory. The total AOF results measured on PIGE were compared with the target PFAS analysis by LC-MS/MS.

Results/Lessons Learned:

We will present the findings from the analysis of drinking and surface water samples collected in northern Indiana. This presentation will include a comparison of results obtained through PIGE and LC-MS/MS. Initial findings indicate that PIGE frequently detects higher levels of organic fluorine compared to LC-MS/MS. This difference is attributed to the likely prevalence of ultrashort-chain PFAS in real-world water samples.

Furthermore, we have determined the capture efficiencies of longer-chain PFAS, specifically C5-C10, as well as the relative capture efficiencies of ultrashort-chain PFAS, such as C2 and C3, using our SPE method. These results will also be presented and discussed.

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Daniele Almeida