An optical sensor detects “forever chemicals” in water

Scientists at the University of Birmingham, in collaboration with the German Federal Institute for Materials Research and Testing, have created an optical sensor to detect “forever chemicals” (PFAS) in water.

PFAS stands for per- and polyfluoroalkyl compounds, a group of chemicals that are widely used in a variety of industrial and consumer products, such as non-stick cookware, waterproof outdoor equipment, food packaging, and firefighting foam.

These materials have strong chemical bonds that make them resistant to water and grease, giving them a prominent presence in many products. However, this advantage is a double-edged sword, on the other hand, it gives these materials extreme stability to the environment and do not decompose easily, and they can remain in air and water. Soil and living organisms last a very long time, which is why they are called “perpetual chemicals”.

Studies have linked exposure to some of these substances to harmful health effects, including developmental problems, immune system dysfunction, and an increased risk of developing certain types of cancer. Therefore, efforts are being made worldwide to find tools to detect these in water. To prevent one of the ways they spread through the body, causing these diseases. Side effects. The optical sensor, which was reported in the journal Analytical Chemistry, is part of these efforts.

Image 3: Production of chemicals from waste water relies on solar energy (Shutterstock)
Environmental contaminants can affect the sensitivity and selectivity of analytical instruments, creating challenges in distinguishing between PFAS and other substances (Shutterstock)

Challenges that created the need for a new solution

Over the years, many different scientific and analytical methods have been used to detect these substances in environmental samples. However, the complex nature of PFAS substances and their widespread use have created challenges in accurately identifying and measuring them quantitatively. These methods include:

  • Analytical methods:

Traditional analytical methods such as gas chromatography and liquid chromatography have been used, but the diversity of PFAS and their varying chemical properties have made it difficult to develop a single method that can effectively detect.

  • Target Analysis:

Some efforts have focused on specific PFAS compounds, often those that are best known or have known industrial uses, and this targeted approach has ignored emerging contaminants.

In addition to the lack of a unified analytical method for measurement and the interest in monitoring one material at the expense of others, the following challenges were presented:

  • 1- Other pollutants present in the environment can affect the sensitivity and selectivity of analytical instruments, creating challenges in distinguishing between PFAS and other substances.
  • 2- Some PFAS substances are found in very low concentrations in the environment, which hinders their detection by conventional methods.
  • 3- The wide variety of PFAS materials makes it difficult to obtain all the reference standards relevant to analytical work.
  • 4- Existing methods are difficult to implement, take a long time and are expensive.
The complex nature of PFAS and their widespread use have created challenges in their accurate identification and quantification (Shutterstock)

Based on these challenges, the research team from the British University of Birmingham, in collaboration with the German Federal Institute for Materials Research and Testing, realized the need for an innovative solution that was easy to implement and could detect substances even in small quantities. Could put. concentrations, and being selective for those substances compared to other pollutants, and above all, it had a low cost, which led them to optical sensors.

Optical does it work?

The new device is an optical sensor that emits red light when exposed to ultraviolet rays, and changes in the fluorescence signal emitted by the metal in the sensor indicate the presence of PFAS substances.

According to the study, the mechanism of operation of this sensor can be simplified as follows:

  • Small particles of light: Imagine that we have tiny molecules that glow when light falls on them. These molecules are made of a metal called iridium, and have lipophilic chains (hydrocarbon chains of 6 and 12 carbon atoms, respectively) attached to them.
  • Special Wire: These chains are like claws of molecules, that is, they help molecules form specific structures.
  • Detection of PFAS substances: When you put these molecules in water containing PFAS, these ingredients will interfere with the molecules, changing the way they glow.
  • Long Incandescent Light: What differentiates these molecules is that they glow for a longer period of time, and we can measure the duration of their glow, and any change in glow tells us about the presence of PFAS substances.
  • Gold Support: These molecules attach to the surface made of gold, helping them to remain stable and not lose their shine.
The sensor is based on iridium metal embedded with lipophilic chains and both mounted on a gold plate (Analytical Chemistry).

detection up to 220 micrograms

“The sensor was able to detect 220 micrograms of PFAS per liter of water, which is appropriate for industrial wastewater,” says Zoe Picramino, professor of inorganic chemistry and photophysics, in a press release issued by the University of Birmingham. “However, more work is needed.” “Optimization to increase sensitivity for detecting nanogram levels, especially in drinking water.”

Piceramino describes his invention as extremely important, saying, “PFAS are used in industrial environments because of their beneficial properties, for example in stain-resistant fabrics, but if they are not disposed of safely, these chemicals pose a real threat to life.” “This prototype is a big step toward finding an effective, fast and accurate way to detect this contamination, helping to protect our natural world and potentially keep our drinking water clean.”

Breakthrough extended applications look forward to the challenge

For his part, Wael Abu Al-Majd, professor of chemical sciences at the Egyptian University in Germany, in a telephone interview with Al-Jazeera Net, praised the results of the study, which provided solutions to the challenges facing the research community. Did. over the years, but he insisted that this achievement should be kept in its general form, which is “not that…” It is still in the laboratory framework, and not intended for large-scale practical application. Has been brought. ,

Abu Al-Majd says there are three questions that should be addressed in subsequent studies, in order for this sensor to be adopted in a practical practical environment, and these questions are:

  • Firstly: How stable is the iridium luminescent metal over time, and how does the sensor hold up in different environmental conditions?
  • Second: Can the sensor provide consistent reliable results over a long period of time?
  • third: How portable is it to make the sensor portable for on-site measurements, especially in situations where immediate response is required?

Knut Roerack, head of the Department of Chemical and Optical Sensing at the German Federal Institute for Materials Research and Testing and co-researcher of the study, promises to address these questions.

“Now that we have a prototype sensor chip, we intend to improve and integrate it to make it portable and more sensitive so that it can be used at the site of a spill and determine the presence of these chemicals in drinking water. To be able to go,” Rorack says. Press release.

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