June 3, 2021, 11 am CDT
“Overview of PFAS Analytical Challenges and Opportunities” by Janice L. Willey
Over the past few years, the analysis of PFAS has been evolving. During this period, PFAS analyses needs have grown from evaluation a few PFAS in drinking water to evaluation an extensive list of PFAS in almost every media imaginable. This presentation will highlight some of the more significant analytical challenges we have faced along the way and provide a brief summary of some of the efforts currently underway to address them.
“Developing Analytical Methods for Comprehensive Profiling of PFAS in AFFF Impacted Environmental Matrices” by Dr. Jinxia Liu ( SERDP Project ER19-1157 Webpage)
This presentation focuses on a SERDP project to develop improved analytical methods for PFAS originating from aqueous film-forming foams (AFFF). Except for drinking water (Environmental Protection Agency [EPA] Method 537), standardized procedures for PFAS analysis in environmental matrices are not readily available. The suite of legacy PFAS routinely analyzed in various laboratories does not capture all the dominant anionic, cationic, and zwitterionic PFAS occurring at AFFF-impacted sites. In this project, we will provide results from extensive optimization and validation experiments to allow establishing standardized methods. We will create guidance to end-users regarding choices of quantitation approaches and associated potential limitations. This presentation will highlight the latest progress made towards improving analytical methods with a focus on the following: (1) compound-specific PFAS methods using liquid chromatography with tandem mass spectrometry (LC-MS/MS) and liquid chromatography high-resolution mass spectrometry (LC-HRMS); (2) determining total PFAS via the Total Oxidizable Precursor assay; and, (3) determining total PFAS via Total Extractable Organic Fluorine content. We will also illustrate to what extent current sample storage and hold time protocols, sample preparation procedures, and instrumental methods for legacy PFAS can be transferred as-is to dozens of newly-identified polyfluorinated analytes.
“Assessing and Mitigating Bias in PFAS Levels during Ground and Surface Water Sampling” by Dr. Jennifer Field ( SERDP Project ER19-1205 Webpage)
This presentation will cover a SERDP project aimed at determining the factors that impact PFAS stratification in water columns (wells and surface water) that may result in artifacts in measured PFAS concentrations. The project team is conducting laboratory experimentation on model groundwater wells and surface water to identify sampling approaches that may introduce bias. Field sampling materials were extracted and analyzed for PFAS background, and databases on field equipment blanks were examined to look for pattens of PFAS background. Field sampling of surface water was conducted to determine if the presence of foam or surface microlayer has the potential to impact measured PFAS in bulk surface water. Other issues, such as storage of samples with and without headspace, are also being examined. As shown by results to date, the greatest potential for impacting measured PFAS concentrations includes foam or the microlayer when sampling surface waters. Equipment blanks from 67 Department of Defense (DoD) bases indicate no systemic bias introduced by field sampling, and stratification in model groundwater wells does not impact measured PFAS concentrations with wells. Field sampling materials are unlikely to cause positive PFAS artifacts unless they come in direct contact with the actual sample. Sampling guidance is being refined to reflect the new findings and offer a science-based alternative to current restrictive field sampling guidance documents.