Published August 13, 2018

There are thousands of per- and polyfluoroalkyl substances (PFAS) in use for countless consumer products. PFAS can make products non-stick or waterproof. They are also used in industrial processes and make up fire-fighting foams used by first responders. With so many types of PFAS in use, EPA researchers have had to use new and innovative tools to gather more information about these chemicals.

Traditionally, sample collection, concentration, and analysis has been time consuming and labor intensive and ultimately, researchers must know what chemicals they are looking for. This traditional approach is called targeted analysis. In targeted analysis, researchers are limited by knowing what chemical, or target, they are looking for and they use a specific method and analysis designed to find that specific chemical.

Over the last decade, there has been a transformation in approaches to understanding how chemical exposures are linked to human and ecological health. Today, researchers can rapidly characterize thousands of never studied chemical compounds in a wide variety of environmental, residential, and biological media. This approach is called non-targeted analysis. It differs from targeted analysis because researchers do not have to know what specific chemical they are looking for in a sample. They can use high resolution mass spectrometry (HRMS), a more sensitive analysis, that helps researchers identify many of the chemicals present in a sample. The HRMS measures the accurate mass of molecules and can find chemicals that were previously unknown. This approach is beneficial not just to researchers, but to States, tribes, and local communities who might want to know more about chemical exposure.

Researchers from EPA and NC State University used the non-targeted approach to understand the impact of industrial discharges in the Cape Fear River in North Carolina. Researchers took sequential samples at locations along the river at specific distances from each other. They then compared what new chemicals occurred downstream relative to an industrial discharge source upstream. When researchers found new chemicals in a downstream sample, they used HRMS to figure out the chemical formula and proposed chemical structure of what they found. Using HRMS they identified many PFAS, including GenX, which is a trade name for a PFAS chemical, in the Cape Fear River. The researchers coordinated with the EPA regional office, the state, and industry to reduce PFAS in the watershed.

Non-targeted analysis is proving to be useful in other communities as well. EPA researchers are currently using this approach to help communities in New Hampshire and New Jersey determine the impact of PFAS exposure. Researchers are including air and char (material that has been burned) samples in this analysis.

While the non-targeted approach helps researchers determine what chemicals might be in the environment, it still takes time to figure out which ones are important in each sample. This is because all chemicals, whether they are naturally occurring or manmade, are visible in a sample using HRMS.

“PFAS stand out from other manmade and natural chemicals because of a property called negative mass defect, which means they contain many fluorine atoms,” says EPA researcher Mark Strynar. “This characteristic helps us isolate chemicals that require further investigation.”

For many chemicals, especially PFAS, there is little known about how they move through the environment. With this new non-targeted approach, researchers can pinpoint what chemicals are in a sample and at what concentrations, as well as how they flow through a river, or move through the air or in soil. This innovative approach is important to states, tribes, and local communities to protect their health and the health of the environment.

Learn more:

Per- and Polyfluoroalkyl Substances (PFAS)