PFAS in water
The issue is not simply that laboratories need to detect more compounds. They increasingly need to detect them at lower concentrations, across larger sample volumes, with defensible results and practical turnaround times.
A recent study in PLOS Water offers a useful example of where the field may be heading.
Researchers at the University of Kansas developed an optimised fast-flow solid-phase extraction method combined with UPLC-MS/MS to quantify 40 PFAS compounds in drinking water at sub-part per trillion levels.
For environmental laboratories, water utilities and monitoring professionals, the study is significant because it focuses on one of the least glamorous but most important parts of PFAS analysis: sample preparation.
Much of the public discussion around PFAS testing focuses on mass spectrometry. In practice, however, the analytical bottleneck often begins before the sample reaches the instrument.
PFAS are usually present in drinking water at extremely low concentrations. To measure them reliably, laboratories often need to process relatively large volumes of water through solid-phase extraction, concentrating the target compounds before LC-MS/MS analysis.
That process can be slow. Existing EPA-based methods can involve long sample loading times, especially when laboratories need to process large batches or increase sample volume to improve detection limits.
The new study directly tackles this problem. Instead of accepting slow SPE flow rates as a fixed requirement, the researchers tested whether much faster sample loading could still deliver acceptable PFAS recovery.
Their results suggest that it can.
The researchers found that fast-flow SPE could substantially reduce sample loading time without compromising recovery for most target compounds.
For a 500 mL sample, loading time was reduced from around 100 minutes to 6 minutes. For a 4 L sample, loading time fell from roughly 800 minutes to 60–70 minutes.
That matters because PFAS monitoring is moving from occasional investigative testing toward more systematic compliance and surveillance programmes. A method that saves time at the preparation stage could make a major difference to laboratory throughput.
This is especially relevant for laboratories handling drinking water samples from multiple utilities, catchments or treatment sites. As PFAS monitoring expands, the pressure will not only be on detection capability, but on repeatability, cost control and sample capacity.
The study achieved method detection limits ranging from 0.01 to 1.12 ppt using the optimised 4 L fast-flow SPE protocol.
That level of sensitivity goes beyond what is needed simply to check many current maximum contaminant levels. Its value lies in giving laboratories more room to detect low-level presence, understand mixtures, monitor trends and identify contamination before it becomes a more obvious compliance problem.
This is important because PFAS regulation is not standing still. The EU has now moved into systematic PFAS monitoring for drinking water under the recast Drinking Water Directive, while the US regulatory framework continues to evolve around enforceable limits, monitoring duties and implementation timelines.
For monitoring professionals, the direction of travel is clear even where specific thresholds remain politically contested. Drinking water providers will need more robust PFAS data, and laboratories will need methods that can support both compliance and early warning.
The researchers also applied the method to tap water samples.
Using the optimised methods, they detected at least 10 PFAS out of the 40 target compounds that were not detected using the existing EPA Method 1633A-style comparison method. Concentrations were reported in the range of 0.19 to 4.10 ppt, with regulated compounds below current maximum contaminant levels.
For laboratories, this shows why lower detection limits matter. A sample can appear clean under one method while still containing measurable PFAS at ultra-trace concentrations under a more sensitive workflow.
That does not automatically mean a regulatory breach or an immediate health risk. It does mean that analytical sensitivity affects what monitoring programmes are able to see.
The study also highlights several practical details that will matter to analytical chemists and laboratory managers.
Nitrogen drying improved detection limits in some cases, but it also caused poor recovery for certain neutral PFAS, including sulfonamides and sulfonamidoethanols. This suggests that laboratories need to be careful when adding concentration steps, as a method that improves sensitivity for one group of compounds may reduce reliability for another.
The researchers also examined syringe filtration and SPE elution volume. Filtration did not significantly affect PFAS recovery under the tested conditions, while a 5 mL elution volume provided the best recovery across the compounds assessed.
These details are important because PFAS analysis is highly vulnerable to small procedural differences. At sub-ppt levels, method design, solvent volumes, sample handling, cartridge performance and background contamination all become part of the measurement system.
One of the most useful findings in the study is also one of the most cautionary.
The researchers found that some PFAS were present at or near the method detection limit even in blank water. This suggests that, as methods become more sensitive, background PFAS contamination can become a limiting factor.
That is a familiar problem for laboratories working with PFAS. Contamination can come from sampling materials, labware, solvents, tubing, filters, instrument components, clothing, packaging or the wider laboratory environment.
As detection limits move lower, quality control becomes more important, not less. Method blanks, field blanks, isotope-labelled standards, contamination audits and strict material selection will become central to confidence in results.
This study should not be read as a replacement for accredited regulatory methods. Nor does it remove the need for full validation across different waters, laboratories and real-world matrices.
Its importance is that it points toward a more practical future for ultra-trace PFAS monitoring.
For laboratories, optimised fast-flow SPE could help increase throughput and reduce preparation time. For utilities, it could support more frequent or more sensitive monitoring. For instrument suppliers, it reinforces demand for workflows that combine high-sensitivity LC-MS/MS with robust sample preparation, contamination control and automation-ready extraction systems.
For regulators and water managers, the study also raises a broader point. As analytical methods improve, the definition of what is “detectable” changes. PFAS that were previously invisible at routine monitoring levels may become measurable, reportable and eventually actionable.
That shift will put pressure on every part of the monitoring chain: sampling plans, laboratory capacity, data interpretation, treatment decisions and public communication.
PFAS regulation is often discussed as a question of limits. This study shows that it is also a question of laboratory capability.
The next phase of drinking water PFAS monitoring will depend not only on what regulators decide, but on whether laboratories can generate sensitive, reliable and affordable data at the scale required.
IET 36.2 Mar/Apr 2026
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