Portable Sensors: The Next Generation of PFAS Detection

Much is known about the exceptional stability and resistance to degradation of PFAS compounds. But when it comes to detection – argues Silvana Andreescu, Professor of Bioanalytical Chemistry at Clarkson University, USA – the field is still playing catch-up.

Researchers are dealing with an enormous number of PFAS compounds – thousands, with different chain lengths, sizes, and functional groups – which makes it incredibly difficult to develop selective detection methods. “Often, we can only target one compound at a time, or maybe a small subclass,” she says. “Detecting degradation products is even harder, because there are no analytical standards available for many of them, even using conventional techniques.”

Then there’s the issue of ultra-low – parts per trillion – detection limits. “The established EPA methods using LC-MS/MS can reach those limits accurately, but they require extensive sample preparation and sophisticated instrumentation – resources that not every lab has access to,” says Andreescu. “And even then, those LC-MS/MS methods only measure a small fraction of the PFAS universe.”

On the regulatory and implementation side, most detection is still centralized. “There simply aren’t enough accredited labs to handle the demand for PFAS monitoring. The analyses themselves are expensive and slow – turnaround times can be weeks or even months, with costs ranging from roughly $200 per water sample to $600 or $700 for biological samples.”

So, given the scale of monitoring required – especially for regulatory enforcement – that combination of cost, complexity, and limited capacity becomes a major bottleneck. As a result, there is a growing movement – spearheaded by researchers like Andreescu – to take PFAS detection out of the lab and into the field.

In this interview, Andreescu discusses how advances in portable sensing technology – from optical and electrochemical sensing to new functional materials designed for molecular recognition – could complement gold-standard LC-MS-based approaches and expand global monitoring capacity.

Given the high cost and slow turnaround of centralized lab testing, is there growing interest in field-based or in situ approaches?

Yes, absolutely – this is becoming a very active area of research. If you look at the literature from the past five years, there’s been a clear surge in new analytical methods and sensor technologies for PFAS detection. The interest is being driven by several factors: the high cost of current lab-based methods, increasingly strict regulatory limits that demand broader monitoring, and, of course, scientific curiosity – because PFAS present such a fascinating analytical challenge.

If we can develop reliable, low-cost, field-deployable sensors, that would be a real breakthrough. They could make large-scale monitoring feasible, reduce the cost and workload for centralized labs, and even be used in real time to optimize remediation – for example, by measuring PFAS levels before and after treatment directly in the field.

There’s a huge practical need and a clear market opportunity here, which is why so much momentum is building around field-based sensing right now.

How do these newer sensing approaches compare with traditional techniques in terms of sensitivity and performance?

There’s no question that LC-MS/MS remains the gold standard. It’s highly reliable and can distinguish and quantify many PFAS compounds – at least those currently on regulatory lists. But it’s also slow, expensive, and resource-intensive. You need specialized personnel and facilities, and not every analytical lab has that capability.

By contrast, the new generation of low-cost sensors can’t yet match LC-MS/MS for accuracy, but they’re improving fast. In recent years, we’ve seen promising developments in portable, lower-cost optical, fluorescence, and electrochemical devices. Some of these are already achieving regulatory limits in the parts-per-trillion range – occasionally even sub-ppt – and showing good selectivity for individual PFAS such as PFOA or PFOS, particularly when materials with molecular recognition are used.

That said, many of these devices still detect at higher concentrations, well above EPA limits, and often need pre-concentration steps. Reliability is another hurdle. Most are still at the proof-of-concept stage and haven’t been widely tested on real-world samples, so they’re still maturing in terms of robustness and consistency.

And there’s a deeper question too: do we really need a sensor for every single PFAS? That’s probably impossible. A more practical goal is to develop screening-type sensors – tools that can rapidly scan thousands of samples and flag a smaller subset for confirmatory LC-MS/MS analysis. I think that kind of tiered approach offers one of the most promising paths forward for PFAS detection.

What sensing strategies or technologies do you see as most promising – and what makes them stand out?

In terms of deployability and performance, most current PFAS sensing strategies fall into three main categories: spectroscopic and electrochemical approaches. On the optical side, we’re seeing fluorescence-based and Surface-enhanced Raman spectroscopy (SERS) ; on the electrochemical side, a variety of voltammetric and impedance-based devices. The big advantage of these platforms is that they rely on low-cost, widely available instruments – things like UV-Vis spectrometers, fluorimeters, basic electrochemical readers, or Raman instruments. If we can develop reliable PFAS sensing methods using these tools, they could be implemented in almost any lab with fairly standard equipment.

Electrochemical methods tend to be more sensitive than optical ones, and most of the platforms that have achieved low parts-per-trillion detection limits fall into this category. These are, in my view, the closest to being truly field-deployable while still maintaining the required sensitivity.

Another major trend is the use of advanced functional materials to improve selectivity – giving sensors molecular recognition capabilities for specific PFAS. Molecularly imprinted polymers (MIPs) are a classic example, and metal-organic frameworks (MOFs) have also shown strong potential for PFAS capture. In some cases, researchers are combining these materials into hybrids that enhance both binding and signal response.

Most proof-of-concept sensors are still focused on individual PFAS such as PFOA, PFOS, or GenX, or they respond more broadly to carbon-fluorine bonds across classes. But as building blocks, these material-enhanced optical and electrochemical platforms represent some of the most promising directions for future PFAS sensing.

Could you tell me a bit about your own work on PFAS sensing?

My background is in developing sensors and sensing systems – I’ve been doing this for about 25 years – and over that time my group has created a range of platforms for different analytes. I first became interested in PFAS about five years ago, when the challenge was put to me very directly: could we design sensors capable of detecting PFAS at parts-per-trillion levels, even in complex matrices like drinking water, groundwater, or wastewater?

That became our starting point. We evaluated the optical and electrochemical materials already in our lab – some of which showed affinity for fluorinated species – and began adapting them specifically for PFAS detection. From the outset, we defined a set of design goals: high sensitivity (down to EPA ppt-level limits), adaptability to standard laboratory instruments, cost-effectiveness (ideally just a few dollars per probe), simplicity of operation, and scalability for large-scale production. We also wanted the platform to work either for specific compounds such as PFOS and PFOA, or for broader screening of total or subclass PFAS.

Because there are no natural receptors or antibodies for PFAS, we couldn’t simply create a lateral flow test – which made the project more complex. But after about five years of work, including contributions from three PhD students, we now have two functioning sensor platforms, one of which looks particularly promising.

Our main platform is an electrode-based sensor that can detect PFOA and PFOS at or below the EPA’s ppt limits. All reagents are built directly into the probe, so the workflow is remarkably simple: incubate the sample for a few minutes, then measure the electrochemical signal. No additional reagents are required beyond buffer and sample – it operates almost like a glucose meter.

We’ve since tested real-world samples, including industrial wastewater, and compared the results with LC-MS/MS. While it doesn’t quite match that gold-standard precision, the results showed about 85 percent agreement – which is very encouraging for a portable, field-deployable platform that’s still being refined.

Looking ahead, what are the biggest barriers to wider adoption of PFAS sensing technologies?

Honestly, it’s a bit of everything. Technically, we’ve demonstrated that our sensors can reach parts-per-trillion detection limits, but so far that’s been at the bench scale, on a relatively small number of samples. The next major step is to prove they can perform consistently across hundreds, or even thousands of real-world samples from environmental and industrial settings.

That means collaborating closely with field practitioners to understand what kinds of samples and matrices they encounter, what typical PFAS mixtures and concentration ranges look like, and what potential interferences might occur. We’ve been driven by scientific curiosity so far, but moving beyond the lab really requires partnerships with industry, utilities, and local communities – and we’ve already begun building those connections, particularly with drinking water providers.

On the regulatory side, the challenge is validation. LC-MS/MS remains the accepted standard, so any new sensor platform has to go through formal performance benchmarking in multi-lab studies and gain endorsement from the wider community – not just from academic groups.

That’s where the field is right now. There are many exciting proof-of-concept sensors being published, but only a few will advance to real-world deployment. The ones that succeed will be those that bridge that gap – demonstrating robust, reproducible performance outside the lab, at scale.

Are you optimistic about the prospect of pushing PFAS sensors from the lab into real-world use – in the near future?

From our experience and review of the PFAS sensing literature, it’s clear this is a difficult challenge – analytically, technologically, and from a regulatory perspective. But there’s a tremendous amount of work happening right now.

I’m optimistic that within the next year or two, we’ll see some of these technologies move beyond the lab – probably starting with PFOA and PFOS, where regulatory attention is strongest. The critical next step is interlaboratory validation with real-world samples – and that’s something several of us are actively working on right now.

For real-world use, we’ll need stronger engagement from industry and local communities. As academics, we can push the science forward, but scaling and deploying these tools requires true collaboration – people on the ground who can help validate and implement them in practice. That’s the step that will really make the difference.

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