Forever chemical detection method “big step forward” which may help to keep drinking water clean

Forever chemicals are exactly what they say they are – chemicals which persist in the environment forever, and worryingly, they are ubiquitous. They’ve largely gone unnoticed until relatively recently, and scientists are developing new approaches for detecting them.

Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) are manufactured fluorine chemicals, and scientists from the UK and Germany have developed a new approach for detecting pollution from these forever chemicals in water through luminescence. The findings have been published in Analytical Chemistry.

What are PFAS?

PFAS are manmade chemicals which are non-degradable and accumulate in every environment. They are used in several different industries – from food packaging to semiconductor production and car tires. The toxic pollution they cause, particularly in water, has been rising in recent years.

“PFAS are used in industrial settings due to their useful properties for example in stain-proofing fabrics. But if not disposed of safely these chemicals pose a real danger to aquatic life, our health, and the broader environment,” explains Professor Zoe Pikramenou, Professor of Inorganic Chemistry and Photophysics at the University of Birmingham.

“Being able to identify ‘forever chemicals’ in drinking water, or in the environment from industrial spills is crucial for our own health and the health of our planet,” adds Stuart Harrad, Professor of Environmental Chemistry.

“Current methods for measurement of these contaminants are difficult, time-consuming, and expensive. There is a clear and pressing need for a simple, rapid, cost-effective method for measuring PFAS in water samples onsite to aid containment and remediation, especially at (ultra)trace concentrations. But until now, it had proved incredibly difficult to do that.”

Harrad and Pikramenou co-led the design of a new prototype sensor which detects perfluorooctanoic acid (PFOA).

“The sensor works by using a small gold chip grafted with iridium metal complexes. UV light is then used to excite the iridium which gives off red light,” explains Professor Pikramenou. “When the gold chip is immersed in a sample polluted with the ‘forever chemical’, a change of the signal in the luminescence lifetime of the metal is observed to allow the presence of the ‘forever chemical’ at different concentrations to be detected.”

“So far, the sensor has been able to detect 220 micrograms of PFAS per litre of water which works for industrial wastewater, but for drinking water we would need the approach to be much more sensitive and be able to detect nanogram levels of PFAS,” she adds.

Nanochip for the nanoscale

Surface and sensor scientists at Bundesanstalt für Materialforschung und -prüfung (BAM), Germany's Federal Institute for Materials Research and Testing worked on the assay development and dedicated analytics at the nanoscale.

Dan Hodoroaba, head of BAM’s Surface and Thin Film Analysis Division, highlighted the importance of chip characterisation: “Advanced imaging surface analyses are essential for the development of dedicated chemical nanostructures on customised sensor chips to ensure optimal performance.”

“Now that we have a prototype sensor chip, we intend to refine and integrate it to make it portable and more sensitive so it can be used on the site of spills and to determine the presence of these chemicals in drinking water,” adds Knut Rurack, who leads the Chemical and Optical Sensing Division at BAM.

Professor Pikramenou concluded: “This prototype is a big step forward in bringing an effective, quick, and accurate way to detect this pollution helping to protect our natural world, and potentially keep our drinking water clean.”