Researchers at the National Institute of Standards and Technology (NIST) have developed a database that can help others identify and categorize PFAS in chemical analysis data.
The database contains "untargeted" chemical analysis data that includes information on both known PFAS and unknown PFAS that may be lurking in a sample. The database is the first of its kind and may be useful for environmental monitoring and other applications.
Require Central Database for Latest PFASs
Government agencies and environmental organizations are increasingly monitoring PFAS, but there are thousands of different chemical structures of PFAS, only a small fraction of which can be measured with high confidence.
“
There is no single authority on what is PFAS or what makes up PFAS,” said NIST biologist Jared Ragland. “
We know what a few hundred of them look like structurally, but there could be 9,000 or more possible different PFAS structures. That's no small problem.”
For example, a community may want to know if there are significant levels of PFAS in a local lake used for fishing, so local officials send samples to a lab for testing. But most PFAS aren't in the suite of chemicals included for quantitative analysis, so the lab tests will miss them.
In addition, the labs may have incomplete or outdated chemical data on PFAS. Because additional PFAS are constantly being discovered, it is difficult to maintain a central database that collects and organizes the scientific community's knowledge of known and unknown PFAS chemical structures.
Using Mass Spectrometer to Detect Known PFAS
PFASs were first used in consumer and industrial products in the 1940s because of their chemical properties, such as their ability to resist heat, oil, and water.
Some types, such as perfluoroctane sulfonate (PFOS), have been replaced over the years, but in general these chemicals break down slowly and leach into the environment. They have been found in our soil, air, food, and water, and have been used in a variety of manufacturing processes, consumer products, and fire suppressants.
To monitor where these chemicals are found and determine where they end up in the environment, scientists need to be able to identify them. An analytical instrument called a mass spectrometer allows scientists to detect known PFAS and understand newly observed PFAS. This instrument produces a series of lines on a graph that form a unique pattern that acts like a molecular "fingerprint" of a chemical compound.
This new database contains this high-resolution mass spectrometry data and currently includes spectra for 132 PFAS. Each entry is accompanied by contextual information, such as instrument settings and sample types used. It also includes NIST's "suspect" list of nearly 5,000 curated chemical compounds that are highly likely to be PFAS.
Can Identify Chemicals Beyond PFAS
The database can be used to identify PFAS in various sources, such as wastewater, tap water, surface water and groundwater, for environmental monitoring. “
The goal is that the database will be helpful in identifying PFAS across the board and in characterizing novel PFAS to answer questions about environmental health, toxicology, exposure risk, and remediation effectiveness,” Ragland said.
Researchers trained in data analysis will find the database particularly useful. But NIST researchers hope to make the database more accessible to all users. They have created a user guide that provides step-by-step instructions on how to use the database. The database is also portable, meaning it can be used offline, added to and shared among researchers, and comes with a software toolkit on GitHub. Researchers can reuse elements of the database to organize and identify chemicals other than PFAS, such as other emerging contaminants or pesticides in food.
Scientists can easily share the database so they can collaborate on finding new patterns in the PFAS data, for example. They can also use the database to develop new tools or data processing methods to identify specific types of PFAS that don't yet have high-quality mass spectrometry data. “
Researchers in this field still lack good methods for sharing data directly with others, so that's a barrier we hope to begin to break down,” Ragland said.
Source: NIST