PFAS reference materials set to raise quality standards

Per- and polyfluoroalkyl substances (PFAS), often described as ‘forever chemicals’, are at the center of one of the most active areas of environmental and public health testing. Growing concern over their known and still-emerging effects on human health is driving significant analytical demand, from testing drinking water and soil to food packaging, food matrices, biota, and other areas of concern.

As these applications expand, laboratories are under mounting pressure to detect more compounds, at lower levels, across more complex matrices. Reference standards underpin confidence in those results, but sourcing materials that are suited to the application, available when needed, and of the right quality remains a major challenge.

It is a challenge Dr. Jason Herrington, Vice President of the Reference Standards Business Unit at Restek, sees every day with testing laboratories across the PFAS continuum. In this SelectScience^® interview, he discusses how Restek is pushing the limits of reference standard purity and consistency, addressing the growing need for branched PFAS testing, and working closely with labs to support their evolving goals.

A new supplier of high-quality PFAS reference standards

As demand for PFAS analysis has accelerated, so too has the need for reliable reference standards. Yet for many laboratories, sourcing these materials has not always been straightforward. Herrington explains that the market has historically offered limited supplier choice, creating practical challenges around availability, shipping, and speed of delivery.

“The biggest single gripe coming from customers was the need for alternative vendors,” he explains. “They were just desperate for anybody else to be offering reasonably priced, high-quality materials that could be readily available.”

This was the catalyst for Restek’s entrance into the market. The company began building its dedicated PFAS reference standards capability in 2024, launched its first materials at the end of that year, and spent 2025 building its portfolio.

Restek’s initial focus was on native PFAS standards, building a core portfolio of around 40 to 45 compounds included in many of the major standardized methods used globally across drinking water, wastewater, and soil testing.

“For a large number of the laboratories in the industry, that’s all they’re going to want,” Herrington says. “For example, the US EPA Method 537.1 calls for 18 compounds – no more, no less.”

However, he notes that parts of the market are moving well beyond standardized lists, driven not only by regulatory agencies and academic research, but also by competition between contract laboratories. For some labs, broader PFAS panels have become a way to differentiate their services. “If lab A can report 42 compounds, but lab B can report 46, that becomes a competitive advantage,” he says. “The most aggressive and progressive contract labs in the world now have native compound lists approaching 100.”

This creates a multifaceted challenge for reference standard suppliers: supporting the core compounds required by established methods, remaining competitive in the supplier landscape, and working closely with progressive laboratories as they push toward broader analyte panels.

Restek’s approach to this is not to expand its portfolio for expansion’s sake, but to work directly with laboratories to understand which new standards are genuinely needed. “Our differentiation is that we’re working with labs side by side,” Herrington explains. “The instant a lab has a need, and they communicate that to Restek, we work on the sourcing, the synthesizing, and the purification to provide that offering as quickly as possible.”

The push for 99.8% purity

Access to reference materials is only part of the challenge. As analytical methods become more sensitive and instruments push detection limits lower, laboratories also need materials of higher purity. Historically, environmental reference standards at 97% or 98% purity may have been suitable for conventional testing, but that is increasingly no longer the case for PFAS analysis. “With triple quad LC-MS/MS pushing down to part-per-trillion, part-per-quadrillion levels, 97 to 98% pure is just not an option anymore,” says Herrington. “You see that 2% impurity clear as day, and now it’s convoluting your analysis.”

That unexpected peak may raise questions about whether the signal is coming from the standard, the sample, the solvent, the preparation workflow, or the instrument. And troubleshooting those questions takes time and can reduce confidence in the result.

To support ultra-low-level detection and deliver the accuracy necessary for the defensible data labs report, Restek’s PFAS reference materials are produced to 99.8% purity. “At 99.8% pure, we can have the utmost confidence that those impurities will not show up and not cause headaches and heartaches for labs,” he says. “They can know it’s not the standard.”

Herrington describes this approach as serving the “top one percenters,” with the view that materials robust enough for the most demanding laboratories will also support the wider market. “If we can stay with the top 1%, we can service everyone,” he says. “A lot of suppliers are offering 97 or 98% pure, and for some customers that clearly works, but in my opinion, that is just not going to hold up in the long game.”

Early feedback suggests the performance of Restek’s standards speaks for itself. “They test it, they see how good it is, and then they’re hooked,” Herrington enthuses, adding that customers are often even more pleased to find that this level of quality does not come with a premium price tag.

Cracking the branched PFAS puzzle

Another emerging challenge in PFAS testing is the need to detect both linear and branched compounds – isomeric forms linked to how PFAS were originally manufactured. Electrochemical fluorination, widely used from the early 1950s to the early 2000s, produced a mixture of linear and branched isomers, while fluorotelomerization, which later became the primary manufacturing route, produces almost exclusively linear compounds.

Linear and branched PFAS can differ in how they move through environmental matrices, how they accumulate in biota, and how they are eliminated from the body. As a result, measuring both forms can provide useful insight into exposure patterns and potential sources.

But despite this analytical need, access to suitable branched reference standards remains limited. “We know customers are seeing certain PFAS hits in real environmental samples, and there is not a currently available commercial branch variant,” Herrington says. “So now the onus is on us to find a way to source it, synthesize it, purify it, and offer it.”

The ratio of linear to branched material is also critical. Electrochemical fluorination typically produces around 70–80% linear and 20–30% branched material. A standard with too much branching may not reflect what laboratories are seeing in real samples, while too little branching may disappear at low calibration levels. “The challenge is not only hitting the ‘Goldilocks zone’ of around 15 to 30% branched, but then delivering that at the 99.8% purity level,” Herrington adds.

Delivering consistent quality that holds over years

The last challenge Herrington raises is consistency. Laboratories need reference standards they can rely on from one lot to the next. Any variation in purity, composition, or branching profile can introduce uncertainty, affect calibration, and complicate long-term analyses.

Restek’s answer is to make materials in bulk, producing and holding enough material to support around five years of consistent supply. “When we generate a material like a branched PFOA, we target a five-year quantity, so that when that material comes out of Restek for the next five years, every lot will be dead on,” he explains.

This also means taking the time to get materials right before releasing them. “I have two materials that I know people are clamoring for right now,” he says. “I’ve had them since January. I just haven’t had them at 99.8% pure.”

“I know competition already sell this at 97 or 98% pure, but that’s just not the game we’re playing,” he continues. “It’s going to take that extra time to get it right and then get it out there.”

For Herrington, this is central to Restek’s approach to partnership, listening to what laboratories need but not compromising on quality to meet short-term demand. “Purity, consistency, availability, and then last but not least, reasonably priced,” he concludes. “That’s the cornerstone of our whole program.”