Luminescent sensor detects ‘forever chemical’ pollution in water

PFAS or ‘forever chemicals’ are manufactured fluorine chemicals that are used widely in industries ranging from food packaging to semiconductor production and car tires. They are non-degradable, accumulate in the environment and concerns regarding the toxic pollution they cause have been rising in recent years.

In a statement, co-design lead Stuart Harrad, Professor of Environmental Chemistry at Birmingham University, said: “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.

“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.”

The researchers have created a prototype model which detects the ‘forever chemical’ perfluorooctanoic acid (PFOA). The approach uses luminescent metal complexes attached to a sensor surface. If the device is dipped in contaminated water, it detects PFOA by changes in the luminescence signal given off by the metals.

Professor Zoe Pikramenou, Professor of Inorganic Chemistry and Photophysics who co-led the design, said: “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. 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 220μg 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.”

The team collaborated with surface and sensor scientists BAM in Berlin for the assay development and dedicated analytics at the nanoscale. Knut Rurack, who leads the Chemical and Optical Sensing Division at BAM, said: “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.”

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