New Pollutants: Analyzing Soil Samples for a Newly Discovered PFAS Becoming Another

Written by: Sophia Cunningham

The government scientist: someone whose stereotype is strange experiments in a lab you need special clearance to even get into. There are possibly cutting-edge chemicals and secret aliens involved. I got to work in a government lab this summer, and while there weren’t any aliens, I did get to work with new chemicals – more specifically, at the EPA to do research on newly discovered forms of PFAS.

PFAS stands for polyfluoroalkyl substances, which is a large group of chemicals characterized by chains of carbon atoms that have fluorine bound to any “free” bond spots, rather than the more typical hydrogen. They’ve been in the news lately as a result of contamination in the Cape Fear River caused by Chemours; many of them have been identified as toxic, with six recently getting standards that set a maximum limit on their concentration in drinking water. Naturally, research on these compounds is important to keeping both people and the environment safe, and that made me motivated to research them this summer at the EPA.

I specifically worked in the lab of Dr. Mark Strynar in the EPA’s Research Triangle Park facility. His lab specializes in using mass spectrometry, or simply MS, to identify new compounds in the environment – particularly PFAS. MS is a technique used to find out what chemicals are in a mixture you’re analyzing, which makes it especially useful for any kind of pollution research. Organizationally, The lab is under the EPA’s Office of Research and Development, which is exactly what it says on the tin – research and development, and that is what I did at my internship.

My specific research project was on one of the new compounds that they discovered. The compound in question was theorized to turn into Gen X, when absorbed and processed by soil microbes. Gen X is one of the six PFAS with a drinking water standard, meaning that it’s critical to the EPA’s interests to find out if there could, in practice, be more of it than there seems. My job was to test this hypothesis by putting the new compound into soil samples, and then analyzing those samples week by week to see if Gen X appeared, which would tell me that the microbes were doing what we expected.

Over the course of four weeks, I got to take samples from each of the flasks of soil, prepare them, run them through MS, and then analyze the resulting data. Preparation consisted of scooping out a gram of soil from each flask, and then putting it into a tube with solvents intended to dissolve chemicals off of the surface of the soil. Those tubes were then sonicated – the same process done to clean jewelry – to physically knock chemicals off of the soil. The tubes were then put into a centrifuge to separate the solid soil from the liquid solvent. The solvent could then be pipetted out and into the special tubes used for mass spectrometry, and then analyzed.

Week by week, the MS showed that Gen X levels were going up with time, suggesting that our hypothesis was correct. However, it came with the hangup that the initial compound had bound to the soil, so it couldn’t enter the solvent and as a result didn’t show up very well in MS. As a result, we only had evidence of Gen X being made, but not what was being used to create that thing, even if we felt confident theoretically that it was our chemical. A proper scientific conclusion needs something more definitive, so the case wasn’t closed quite yet.

After the four-week study was completed, we tried to get around this problem by extracting the microbes that were actually doing the job from the soil that was causing the problem. I’ve never worked in microbiology before, so here I had to do proper research so that we could develop a basic process. I got to look at papers and textbooks, and also got to talk to proper microbiologists at the EPA. It was really interesting to learn about a very different discipline, and I’m glad I got to, even if I don’t really have any intent to do more microbiology.

One of the things that I learned during my research was that many microbes don’t readily extract from soil, and unfortunately this ended up being the case for the microbes that are responsible for the reaction I was researching – there was no Gen X made during this part of the experiment. Even though this part ended up being a bust, it taught me that it’s important to research before an experiment. If I hadn’t learned about the difficulties of growing soil microbes, I would have been very confused when nothing was being made, and probably be much more frustrated. 

Even if it didn’t end in a perfect, definitive result, I still really enjoyed this internship. I got a lot of experience doing the kind of environmental research that I want to do in the future. I like getting to do chemistry and working hands-on with samples – I’ve taken them before, but I haven’t gotten to do all the steps between that and data analysis until now. Knowing that what I’m doing matters for real-life chemical regulation is an incredible feeling, and I hope I get to do more of that type of research in the future.

Overall, I was incredibly grateful that I got to have this opportunity. This internship taught me about what my later career could look like, while also giving me the experience needed to then do it. In the future, I hope to do similar work by getting a PhD in chemistry. Few people get to work directly with the EPA, and not only did I get to do that here, but I was also able to work on research that matters.