New Material Could Improve People’s Health and Reduce Pollution

A material that holds the key to cheap, fast and portable new sensors for a wide range of chemicals has been developed by chemists at the University of Texas at Austin. The innovation could drastically reduce the costs associated with cleaning accidental chemical spills, remediating old industrial sites, detecting radioactive contamination in drinking water and operating medical and research imaging devices.

Humphrey and his team are developing paper dipsticks that can quickly and cheaply identify a wide range of chemicals in an uncharacterized sample. Courtesy of Samuel Dunning and David Steadman/University of Texas at Austin.

"A company with an abandoned chemical plant that has barrels of unlabeled solvents or a public utility concerned its water supply has been contaminated today face a cumbersome process of identifying the chemicals before they can start cleanup," said Simon Humphrey, associate professor of chemistry who led the research. "It's costly and can take two or three days. We can now do that with a rapid, on-site method — and that difference could improve people's health and reduce pollution a lot more efficiently."

The material, called PCM-22, is a crystal made of lanthanide ions and triphenylphosphine. When a chemical bonds to the material and a UV light shines on it, the material emits specific colors of visible light. Each chemical produces a unique eight-factor signature of color and brightness that can be used to identify and quantify it in an uncharacterized sample.

Humphrey envisions disposable paper dipsticks coated with the new material. The user would simply dip one into an uncharacterized substance and then stick it into a UV reader. The device would indicate what components are in the substance based on the colors of light emitted.

Scientists must first calibrate the sensor on known samples to create a catalog of fingerprints that can be used to identify the components of uncharacterized samples. Once this is done, the dipstick-type sensors would be relatively simple to produce, Humphrey said. He and UT Austin share joint patents on the sensor material and on the process of analyzing results; UT Austin's Office of Technology Commercialization has already begun work to license the technology to companies.

Another beneficial feature of PCM-22 is that it can distinguish between two types of water — the ordinary water (H₂O) used in everyday life and so-called heavy water (D₂O), used in the operation of medical and research imaging.

The two types of water are hard to tell apart because they look, and in most cases, behave the same chemically. With D₂O, hydrogen atoms are replaced by deuterium atoms.

Because the new material makes distinguishing between the two types of water simpler, it could become much easier for government agencies to detect the presence of radioactive contamination in drinking water or other bodies of water such as lakes and rivers.

The new material, which is sensitive enough to detect concentrations of ordinary water as low as 10 parts per million in a solution of heavy water, could make it cheaper and faster to verify the purity of heavy water.

The research has been published in the journal Chem (doi.org/10.1016/j.chempr.2017.02.010).