Since 2016, at least 10 methods to measure different PFAS substances that cover all environmental matrices have emerged, according to Bharat Chandramouli, an environmental laboratory product manager for SGS Axys Analytical, a trace organics laboratory based in British Columbia, Canada.

Within the past 10 years, PFAS testing has evolved so that with many of those laboratory methods becoming “fairly standardized workflows” to the point that “in-house methods are also now becoming more and more frequent,” said Chandramouli. This has prompted labs to use methods that provide “relatively predictable data, because PFAS analysis still remains fairly complex,” he said.

Along with the increasing methods used to detect levels of PFAS, the lists of PFAS that commercial labratories can report—including methods for total PFAS detection, not just targeted PFAS—are also increasing, Chandramouli said. The methods used now are non-target analysis, and high-resolution analysis, as well as increased standardization of those methods, he added.

The methods used to detect PFAS within the U.S. are outlined by industry organizations and government, such as the Environmental Protection Agency’s (EPA) method “1633, Revision A” (1633A)—Analysis of PFAS Substances in Aqueous, Solid, Biosolids, and Tissue Samples by LC-MS/MS—which is an update to method 1633 in determining PFAS in aqueous, solid (soil, biosolids, sediment) and tissue samples by liquid chromatography/mass spectrometry (LC-MS/MS). Nonetheless, 1633A is “still in promulgation,” Chandramouli said.

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Furthermore, Chandramouli said the American Society for Testing and Materials (ASTM) “has also gotten into the game with a number of methods.” Those methods include:

• ASTM D8421—the Standard Test Method for Determination of PFAS in Aqueous Matrices by Co-solvation followed by LC-MS/MS—which was developed in response to the use of PFAS in various industrial and commercial products, and have been found to be persistent, bio-accumulative, and ubiquitous in the environment. PFAS have been reported to exhibit developmental toxicity, hepatotoxicity, immunotoxicity, and hormone disturbance. PFAS substances have been detected in soils, sludges, surface, and drinking waters. This is a quick, easy, and robust method to quantitatively determine these compounds at trace levels in water matrices. This test method has been validated using reagent water and waters from sites that include landfill leachate, metal finisher, publicly owned treatment works (POTW) effluent; hospital, POTW influent, bus washing station; power plant and pulp and paper mill effluent for selected PFAS.
• ASTM D8535—the Standard Test Method for Determination of PFAS in Soil/Biosolid Matrices by Solvent Extraction, Filtering, and Followed by LC/MS/MS—which is a test method designed to validated the use of four ASTM reference soils (CH-1, ML-1, CL-1, and SP-1); ASTM reference soil CH-1 that is fat clay (CH)—Vicksburg buckshot clay; ASTM reference soil ML-1 that is silt (ML)—Vicksburg silt; ASTM reference soil CL-1 that is lean clay (CL)—Annapolis clay; and ASTM reference soil SP-1 that is sand (SP)—Frederick sand and four biosolids (Missouri, California, Idaho, and Georgia).

In addition to those standard methods, in-house methods are increasing in frequency, along with an increase in the lists of PFAS substances to more than 100, according to Chandramouli. “Multiple labs can now support not just your standard reference method list, but many, many, many more target PFAS as well,” he said.

Of course, beyond the target analysis methods, there are other add-on type methods that go beyond just a standard list of targets, Chandramouli said. Such a method includes the “total oxidizable precursor, or TOP,” which converts any unknown PFAS precursors into carboxylates, so they can be measured more easily, he said, adding it is an attempt to provide a subset of a total type analysis, that is a precursors of carboxylic carboxylate PFAS. “It’s a very powerful and complex method, but when used right, it gives you very interesting data,” he said.

Furthermore, organic fluorine “is a big focus” in PFAS detection, Chandramouli said. Organic fluorine seeks to determine the total mass of PFAS that might be present by measuring organic fluorine as a proxy. “These methods are usually done with combustion ion chromatography,” which tries to get it into a form where it combusts at a high temperature and from which the fluoride can be measured, he said.

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There are also a few other approaches available that depend on exactly what is trying to be measured, said Chandramouli, who added there is non-targeted analysis, that attempts to determine PFAS without having to measure access to standards or any other information.

“So, essentially, forensic level PFAS analysis is becoming a bit more available in commercial labs, which was not really a commercially available analysis, even a few years back, but now it’s quite a bit more available,” Chandramouli said. In addition, among the latest, “but still emerging” measuring method is “field and sensor tech for real-time PFAS monitoring,” he said.

Also making a presentation during the webinar was Kushan Kompalage, a research associate at Kansas State University’s Water Quality Lab, who said a main focus of the laboratory is measuring emerging contaminants, including PFAS, and the lab has found that agricultural systems within Kansas have more PFAS contamination from industrial sources, consumer products, and from other products such as fire extinguishing forms.

“We have a lot of military presence in Kansas, so a lot of people have been using fire extinguishing forms in those military establishments,” he said.

Furthermore, there are concerns in Kansas about PFAS levels that are in the environment, especially in agricultural establishments and ultimately in agricultural products that are consumed, Kompalage said.

The Water Quality Lab is focused on well water, soil, biosolids, plant materials, and animal tissue, but the laboratory, which is agricultural-focused, has found low concentrations of PFAS in agricultural samples, specifically through meat research, Kompalage said. However, while the concentrations of PFAS in those samples are low, when such agricultural products are consumed, “we infuse PFAS into our bodies,” he said. Such PFAS is accumulated in the body, so the laboratory is developing methods to detect these PFAS contaminants in the environment at lower levels so food products and drinking water are PFAS free, he said.