New Analysis Method Can Detect Forever Chemicals in Under Three Minutes

Per- and polyfluoroalkyl substances (PFAS) used to be household staples, being used in a wide range of grease-proof, water-proof and stain-resistant products. Now, these compounds are more commonly known as “forever chemicals” for their extreme persistence in the environment. Unable to breakdown naturally, these chemicals accumulate and spread over time.

Detecting the presence of PFAS in a given sample is typically a very time-consuming process, requiring lengthy sample preparation. But a new laboratory method developed by chemists at the New Jersey Institute of Technology (NJIT) promises to detect traces of PFAS in just three minutes or less.

The technique has been demonstrated on samples of drinking water, tap water, wastewater, paper food packaging and soil samples in a new paper, published in the Journal of Hazardous Materials.

A rapid lab test for PFAS

PFAS testing is a tricky business. Due to their extreme persistence, PFAS tests need to be carried out on a wide variety of different sample types. Complex samples, such as soil, will present extra challenges as they are likely to contain other minerals and microorganisms that will complicate analysis.

To cope with this complexity, traditional PFAS analysis normally involves some kind of solid phase extraction (SPE) or liquid-liquid extraction (LLE) step to preconcentrate samples prior to analysis. Analysis is most commonly done with liquid chromatography with tandem mass spectrometry (LC-MS/MS) or a similar technique.

Practically, this analysis works very well. But the intricate sample preparation and liquid chromatography steps required are very time consuming.

The new method proposed by the NJIT researchers is based on an ionization technique called paper spray mass spectrometry (PS-MS), a variant on electrospray ionization. In PS-MS, a few microliters of the sample and solvent are applied to a piece of filter paper. With the sample mounted on the wetted paper, a high voltage is applied. This creates an electrospray-like event, sending ions of the analyte towards the mass spectrometer for analysis.

“PFAS can be ionized and rapidly detected by a high-resolution mass spectrometer, which gives a clear view of each PFAS species present and the degree of contamination down to a parts-per-trillion (ppt) level,” said corresponding author Hao Chen, a professor of chemistry and environmental science at NTIJ. “For more complex matrices like soil, we’ve applied a related method called desalting paper spray mass spectrometry (DPS-MS) that washes away salts which normally suppress the ion signal of PFAS. Together, they greatly improve our ability to detect these compounds.”

“Our limit of detection for PFAS is roughly 1ppt [parts per trillion]. For context, this amount has been likened to a drop of water in 20 Olympic-sized swimming pools,” added first author Md Tanim-Al Hassan, a PhD student in chemistry at NJIT.

Rapid testing of water, soil and food packaging

In tests on soil samples, the team were able to identify two species of PFAS from as little as 40 milligrams of soil in under three minutes.

To demonstrate the technique’s use in water analysis, the researchers tested samples of local tap water alongside the filtered fountain water available at the university. The PS-MS technique detected traces of perfluorooctanoic acid (PFOA) – one of the most widely studied PFAS chemicals – in the tap water in just under two minutes. No PFAS compounds were detected in the filtered water.

One of the most interesting applications for this new technique, the researchers say, is its ability to directly measure the presence of PFAS in different food packaging materials by swapping out the regular filter paper for a triangle-shaped sample of food packaging.

In their study, the researchers demonstrated this by analyzing samples of microwave popcorn paper, instant noodle boxes, and fry and burger packaging from two multinational fast food restaurant chains. This analysis revealed 11 different PFAS compounds present in the packaging, including PFOA and perfluorooctanesulfonic acid (PFOS). It is important to note that this study did not examine whether these PFAS might transfer into the food itself. 

“There are thousands of different species of PFAS, but we’ve yet to understand the extent of their distribution in our environment because the current testing methods are costly and time-consuming, taking hours for sample preparation and analysis in some cases,” said Chen.

“What our study demonstrates is a much faster, sensitive and versatile method that can monitor our drinking water, land and consumer products for contamination in minutes.”

Improving our understanding of forever chemicals

The researchers believe that their new approach could significantly speed up the study of PFAS compounds and help to better address the accumulation of PFAS in the environment.

“The EPA has already proposed to establish maximum contamination levels (MCLs) for six PFAS in drinking water nationwide, and PFOA and PFOS are among them,” said Mengyan Li, study co-author and an associate professor of environmental sciences at NJIT. “This analytical method could facilitate more intensive screenings for toxic PFAS that may be needed under such a proposal to protect the safety of our water supply.”

The new rapid detection method is already being adapted for use alongside other cutting-edge PFAS remediation techniques being developed by the NJIT’s BioSMART Center.

“Remarkably, in our lab we were able to couple this analytical method to a novel degradation catalyst, which degrades 98.7% of PFAS in drinking water samples within three hours,” reported Wunmi Sadik, study co-author and chair of NJIT’s department of chemistry and environmental sciences.

“This work may have a national impact, but the immediate effect will be felt in the Northeast area,” she continued. “Roughly 10% of 9.2 million New Jersians have high levels of perfluorooctanoic acid in their drinking water compared to the national average of 1.9%.”

Reference: Hassan MdTA, Chen X, Fnu PIJ, et al. Rapid detection of per- and polyfluoroalkyl substances (PFAS) using paper spray-based mass spectrometry. J Hazard Mater. 2024;465:133366. doi:10.1016/j.jhazmat.2023.133366

This article is a rework of a press release issued by the New Jersey Institute of Technology. Material has been edited for length and content.