Small gold chip helps detect 'forever chemicals' in water

Concerns regarding the toxic pollution caused by PFAS or ‘forever chemicals’, particularly in water, have been rising in recent years.

PFAS are manufactured fluorine chemicals that are used widely in different industries — from food packaging to semiconductor production. They are non-degradable and accumulate in the environment.

To combat this problem, scientists from the University of Birmingham and the Bundesanstalt für Materialforschung und -prüfung (BAM), Germany’s Federal Institute for Materials Research and Testing, have developed a new method for detecting pollution from forever chemicals in water through luminescence. Their findings have been published in the journal Analytical Chemistry.

“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,” said Stuart Harrad, Professor of Environmental Chemistry at the University of Birmingham, who, with colleague Zoe Pikramenou (Professor of Inorganic Chemistry and Photophysics), co-led the research.

“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 said.

The researchers created a prototype model that 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.

“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,” Pikramenou explained.

“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.”

In order to develop an assay and dedicated analytics at the nanoscale, the team has collaborated with surface and sensor scientists at BAM in Berlin.

“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,” said Knut Rurack, who leads the Chemical and Optical Sensing Division at BAM.

“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. 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,” Pikramenou concluded.

Image credit: iStock.com/Hyrma