COMMENTARY: How Can Mass Spectrometry Techniques Identify and Curb ‘Forever Chemicals?’

Akron water supply lab
By Craig Butt

As government regulators seek to limit per- and poly-fluoroalkyl substances (PFAS) – which are chemicals linked to a range of health and environmental risks – testing for these chemicals has proven challenging. Called “forever chemicals” because of the extreme resistance to breakdown in the environment, PFAS can seep into groundwater and soil, contaminate food and crops and ultimately endanger human health. Due to the dangers these chemicals pose, regulators are setting limits on PFAS and requiring regular testing to monitor their levels.

While the increase in regulation and testing will be key to limiting the consequences of PFAS, this effort is no simple task, especially for water and waste management companies responsible for mitigating PFAS contamination. There are an estimated 5,000 PFAS chemicals, many of which are not well characterized or understood. However, new technology like accurate mass spectrometry makes defining and analyzing these chemicals possible in this rapidly evolving regulatory landscape.

The Challenge to Identifying PFAS

Earlier this year, the European Chemicals Agency proposed restricting PFAS in firefighting foams across the European Union. In the United States, the Environmental Protection Agency (EPA) initiated a Strategic Roadmap in 2021 that proposes a three-year plan for tackling PFAS along three pillars: research, restrict, and remediate. Earlier this summer, the EPA announced drinking water health advisories for four PFAS, offering technical information to guide water quality monitoring and the use of technology to reduce PFAS. These government actions make the detection and understanding of PFAS more urgent than ever.

There are two methods used to analyze PFAS in water, soil and other solid materials: targeted and non-targeted analysis. Targeted analysis is used to detect and quantify levels of PFAS analytes that have already been defined. The EPA has published several targeted methods for detecting PFAS in drinking water, groundwater, surface water and wastewater, as well as in soil, fish tissue, and other solids. However, the shortcomings of targeted analysis are that it cannot be used to discover new PFAS analytes and most methods can only monitor up to 30 PFAS chemicals, a very small fraction of 5,000 known PFAS produced commercially.

Newer, non-targeted analysis using high-resolution accurate mass spectrometry help researchers identify novel, unknown PFAS analytes. These techniques could be invaluable in the effort to prevent PFAS from entering the environment and endangering human health. Non-targeted analysis entails the unbiased detection of all compounds within a sample followed by sophisticated data processing techniques to confirm the identity of the PFAS chemicals detected. This type of detective work often involves looking at how molecules break apart, much like a how puzzle pieces fit together. Another important advantage of non-targeted analysis is the ability to retrospectively look at previous data when newer information is uncovered.

Characterizing PFAS ‘Dark Matter’

Researchers who are using non-targeted techniques to characterize unknown, or “dark matter” PFAS in water and soil, use sensitive and selective accurate mass, as well as intuitive software that can quickly process large amounts of data. Recent studies illustrate how effective these methods can be in expanding the universe of known PFAS chemicals.

One such study, led by researchers at Harvard’s John A. Paulson School of Engineering and Applied Sciences, analyzed PFAS in aqueous film-forming foam (AFFF) that firefighters have used for decades to extinguish fires involving flammable liquids such as petroleum. The researchers used both an extractable organic fluorine (EOF) technique to measure the total of PFAS content of the AFFF, and a non-targeted mass spectrometry technique to identify the unknown PFAS chemicals that were detected in the standard targeted method. They found that the targeted method only captured 50 percent of PFAS present in a firefighting foam that is no longer on the market, and just 1 percent of PFAS in a foam being used by the military today.

Through non-targeted analysis, the Harvard team was able to characterize 14 previously unidentified PFAS in both contemporary and legacy firefighting foams. The non-targeted approach also allowed them to probe the history of the newly identified PFAS. They demonstrated that because the exact compositions of AFFF mixtures are concealed by confidentially agreements, and they change over time, it’s challenging for scientists to fully understand the PFAS burden and resulting environmental and health risks.

Finding and remediating PFAS in the environment will require continuous vigilance and a collective commitment on the part of the water and waste management industry. One of the most effective and efficient allies in this effort is non-targeted PFAS analysis using sophisticated mass spectrometry tools.

Craig Butt, Ph.D., is a senior staff scientist for food/environmental and global technical marketing at SCIEX, focusing on developing PFAS analysis methods in environmental matrices.

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