Per- and poly-fluoroalkyl substances (PFAS) – formerly named perfluorinated compounds – are a large class of thousands of synthetic chemicals that are used throughout society. PFAS are very durable and resistant to heat, water and oil, meaning they may be found in a wide variety of products, such as raingear, food packaging, waterproof cosmetics, stain-resistant carpets and firefighting foams.
Their widespread use and durability have led to PFAS being found almost anywhere, leading to their accumulation in the environment, food chain and the human body. Resultingly, there is rising concern over human exposure to PFAS and the ill-associated health effects they bring.
International efforts to manage PFAS use are increasing, with a focus on balancing environmental and health impacts alongside practical and economic considerations. While PFAS accumulation is recognized as a global issue, regulatory approaches vary significantly. Some countries have implemented strict regulations, including bans on PFAS in consumer goods, whereas others have less stringent or poorly enforced regulations.
Monitoring PFAS in water systems is of critical importance
Drinking water is a significant source of PFAS exposure and is a prioritized concern due to the primary exposure pathway being ingestion. A further concern is added when the raw source water draw (e.g., public community well) is near an industrial site or where firefighting foams have been used – such as locations in proximity to airports or air force bases.
Regulatory limits for PFAS in drinking water vary internationally, with most countries regulating each PFAS compound individually. The European Union (EU) regulates PFAS as a class and has set parametric values of 100 ng/L for 20 individual PFAS, but with a 500 ng/L limit for total PFAS concentrations within drinking water – with compliance enforcement by January 2026. The United States Environmental Protection Agency’s (US EPA) National Primary Drinking Water Regulations (NPDWRs) were recently enacted in the Code of Federal Regulations, making this the first legally-enforceable maximum contaminant level for several PFAS compounds.
Water authorities are required to monitor six PFAS compounds and take action to remediate if established maximum contaminant levels (MCLs), ranging from 4–10 parts per trillion, are exceeded. State-specific standards may reflect more stringent criteria to address local concerns and better protect public health. However, if a state's standards for any PFAS are not stricter, they must ensure compliance with the established MCLs in the NPDWR.
Other countries are now considering this same comprehensive approach to safeguard the environment from the harmful effects of PFAS, with ongoing efforts to enhance regulatory measures in surface and groundwater. The EU, for example, has the Water Framework Directive which is aimed to protect water bodies from many pollutants, including PFAS. Further, Canadian provinces have set guidelines aimed at limiting PFAS concentrations in the environment – however, these guidelines vary by province.
There are considerable health concerns about PFAS exposure including potential liver damage, cancer, reproductive problems and child developmental effects. Due to the bio-accumulative nature of PFAS, monitoring levels in human biofluids can help gain an understanding of exposure levels and pathways. Since PFAS are not rapidly metabolized or removed from the body, we can gain an understanding of PFAS exposure levels by studying the blood serum content. Therefore, reliable and accurate methods are necessary to continue our understanding of the PFAS burden in humans for purposes such as occupational health monitoring, exposure monitoring and toxicology studies.
Analytical methods play a key role in PFAS detection
There are several analytical technologies and methods used to detect PFAS in drinking water, with their use typically dictated by the type of analysis to be done. For example, if an organization was performing regulated targeted methods for PFAS quantitation, a liquid chromatography tandem quadrupole mass spectrometer (LC-MS/MS) system would be recommended. However, if semi-volatile or volatile ultra-short chain PFAS were of interest, a gas chromatography (GC) MS/MS would be the choice. Regardless of the type of PFAS analysis, for target regulatory work, an MS/MS is the “gold standard.”
For laboratories interested in non-targeted screening, structural characterization or novel discovery, a high-resolution mass spectrometer (HRMS) is essential. HRMS systems typically deliver high sensitivity alongside the specificity of accurate mass measurements (<5 ppm) for precursor and fragment ions, allowing for non-targeted suspect screening of PFAS against a local or online library (e.g., EPA CompTox or National Institute of Standards and Technology PFAS Database). Using accurate mass measurements can help determine the molecular formula of a PFAS compound, distinguishing that compound from those of nearly similar masses.
Another analytical technique is combustion ion chromatography – a technique that pyrolyzes the sample to convert all the fluorine in a sample into fluoride ions which can then be measured by ion chromatography, typically using a conductivity detector. Combustion ion chromatography is a very sensitive analysis technique capable of detecting ions at low concentrations. However, analyses such as this determine total fluorine content, not just fluorine associated with PFAS-defined compounds.
The carrying out of such analytical techniques should not be underestimated. Training and application support are a critical part of a comprehensive PFAS analysis solution, to ensure that laboratory personnel are well-equipped to handle sophisticated analytical tools and methodologies. Furthermore, reliability encompasses all parts of a comprehensive PFAS analytical solution, from sample collection and preparation to reporting results while adhering to accreditation requirements mandated by regulatory bodies. Sample collection, preparation and analysis must mitigate the risk of contamination from external sources, such as collection and preparation containers, solvents or from the analytical system itself. For example, new lots of containers, methanol, vials and other laboratory consumables should be tested for residual PFAS contamination before use.
PFAS detection methods face difficult challenges
One of the most difficult challenges that laboratories face with PFAS analysis is the ubiquitous nature of those compounds. As such, background contamination is found in many places within the laboratory environment. Understanding and mitigating sources of contamination is crucial in PFAS analyses. There are materials and lab supplies that are commonly understood to potentially have PFAS contamination risk: sample containers, foil, pipettes, vials, solvents, and any polytetrafluoroethylene (PTFE) components, to name a few.
Methanol, for example, is important for sample extraction but is also used as a cleaning and washing agent for consumables in experimental procedures. PFAS contamination can differ between manufacturers, lot numbers or even bottles from the same lot. Therefore, it is recommended that each bottle of methanol be tested for residual PFAS contamination before use.
To minimize the impact of residual PFAS contamination in the mobile phase solvents and LC system, a PFAS kit should be installed which chromatographically delays any system or solvent contamination from the analytical peak of interest.
Consistently meeting lower detection limits for PFAS is another pressing issue testing laboratories face, driven by evolving regulatory requirements. As mentioned previously, detection limits are typically in the low part per trillion range, but reaching parts per quadrillion is of high interest since toxicology levels for many PFAS have not yet been studied.
Improved PFAS detection can help enhance public safety
Although there are evolving regulations to manage PFAS use by phasing out or banning certain PFAS, it is not currently practical for their use to be stopped completely. Limiting their use may be the best thing that can be done for now.
For example, the EU has proposed to ban PFAS in non-essential uses under the REACH regulations. Additionally, the US EPA has its PFAS Strategic Roadmap outlining investment in scientific research, preventing PFAS from entering the environment and accelerating the cleanup of contaminated sites to enhance public safety. However, we must remain vigilant in monitoring PFAS and make advancements in detection capabilities and efficiencies. This will enable drinking water providers to more effectively target a wide range of PFAS and other emerging contaminants.
Utilizing advanced technologies like HRMS for screening and premium-grade MS/MS for ultra-trace quantitation and enhanced detection capabilities offers water authorities reliable and robust data. This data supports informed decision-making to implement safety measures, such as optimizing contamination treatment processes using ion exchange resins or granular activated carbon.
Achieving this ultimate goal – protecting public health and enhancing public safety measures – starts with preventing or mitigating contamination while continuing to monitor for compliance.