Scientists and consumers are both concerned about the presence of per-fluoroalkyl compounds (PFAS) in products that millions of people use every day. PFAS can cause serious health problems in humans and animals when they are found in drinking water. Amanda Belunis, a PhD student at the University of Maryland, Baltimore County, has been researching the use of liquid chromatographytandem MS (LCMS/MS), in order to detect PFAS coming from a variety of environmental sources. She spoke to us about methods to detect PFAS. She also described a new method she and the team have developed to improve PFAS detection.
Scientists and consumers are both concerned about the presence of per-fluoroalkyl compounds (PFAS) in products that millions of people use every day. PFAS can cause serious health problems in humans and animals when they are found in drinking water. Amanda Belunis, a PhD student at the University of Maryland, Baltimore County, is studying the use of liquid chromatographytandem MS (LCMS/MS), in order to detect PFAS coming from a variety of environmental sources. She spoke with Spectroscopy She spoke about the methods used to detect PFAS, and she also described a new method she and her team developed to improve PFAS detection.
What are per and polyfluoroalkyl compounds (PFAS)? How can they get into consumer products and contaminate them?
The large range of man-made fluorinated chemicals, including polyfluoroalkyl and perfluoroalkyl substances (PFAS), was developed in the 1940s. PFAS are composed of a fluorinated (per) or partially-fluorinated chain linked to various functional groups. The compounds have hydrophobic and lipophilic properties. They also have thermally stable and generally inert and not reactive properties. These properties are beneficial for a variety of applications such as non-stick cookware and food packaging. PFAS can be found in consumer products through direct methods (for instance, nonstick cookware or water-repellant clothes). PFAS can also be contaminated consumer products like drinking water by indirect means, such as stormwater runoff and waste from nearby industrial facilities.
Recently, you presented a technical poster that highlighted an improved method validation and application to detect PFAS in drinking waters sources following Environmental Protection Agency (EPA), 537.1 (1). What is the difference between this and other methods? What are its benefits?
This method further validates EPA 537.1 for commercial instrumentation. I believe one of the many implementations made to reduce contamination is one of the greatest advantages this method offers. PerkinElmer collaborators also helped us develop a faster method. We modified the liquid chromatography parameters to improve throughput. This reduced the run time from 37 minutes to just 10 minutes.
What were the challenges you faced in developing your method How were they overcome?
PFAS are common in the environment, including in the laboratory. These compounds are used in many products, including materials used in an SPE setup or LCMS system. We discovered that several compounds were present in blanks as we developed our method. Installing a secondary column between the autosampler and the pump was the first step in resolving the issue. delay column. The delay column is used to remove any PFAS from the HPLC pump’s eluents. It delays the elution of background PFA. Background contamination was not completely removed after the installation. This led to further steps being taken, including modifications to both the SPE apparatus and the autosampler to remove any polytetrafluoroethylene (PTFE) or PTFE copolymers. The autosampler contaminated was removed by switching PTFE tubing with polyetherketone material (PEEK). Through troubleshooting and method development, I learned that one of PFAS analysis’s most important aspects is paying attention to the smallest details in order to reduce contamination.
How was high pressure liquid chromatography (HPLC), mass spectrometry(MS) used for the detection of PFASs in drinking water?
LCMS is the most widely used analytical instrumentation to detect PFAS in aqueous environments. Liquid Chromatography is the best choice for separating the PFAS of particular interest. This tandem setup was used for mass spectrometry. It consists of two quadrupoles connected with a collision cell. This detector setup allows you to filter specific mass transitions (precursor/productions) for each analyte, adding an additional layer of selectivity.
Are there other methods than LCMS that were used to detect PFASs in drinking water? If so, please tell us what they were and how they differed from LCMS.
LCMS is a highly sensitive detection method by itself, but sample preconcentration is still necessary to detect environmental levels. This method used LCMS with solid phase extract (SPE). The PFAS found in a sample can be retained on a solid sorbent, and reconstituted in a smaller volume to allow for preconcentration. This method results in approximately 250 mL of sample being collected. After extraction, the preconcentration ratio is 250:1.
How does EPA Method 537.1 impact the way PFAS are detected and reported?
There are many other methods to analyze PFAS. These include combustion ion chromatography (TOF) and gas chromatographymass spectrometry(GCMS). In recent years, however, LCMS has been the most commonly used analytical instrumentation in this field. EPA 537.1 is a validated method that can detect PFAS in drinking waters.
Is there any other situations where EPA 537.1 can detect PFAS, besides the detection in drinking water?
The EPA created 537.1 to detect PFAS in drinking waters. This is a major focus right now. It is possible to take ideas from 537.1 and apply them for the detection PFAS within other aqueous environmental sources. The EPA is also working on other methods to detect PFAS from different sources. Draft method 1633 was published in August 2021 and allows for the detection of PFAS from aqueous, solid, and biosolids.
What are your next steps in PFAS detection and method development?
LCMS is a well-proven technology for detecting PFAS. The next step will be to better understand the problem. Method 537.1 covers only 18 selected PFAS. However, more than 5000 compounds are included in the group. In the future, a further focus will be on increasing method throughput.
A. Belunis and W.R. LaCourse. EPA 537.1 Method Validation to the Detection of Per-and Polyfluoroalkyl Substances in Drinking Water Sources. University of Maryland (2021).
Amanda BelunisShe is a PhD student in the department of Chemistry & Biochemistry at the University of Maryland Baltimore County. She graduated from Towson University with a Bachelor’s degree in Forensic Chemical. Her experience includes instrumentation, sample preparation techniques and method development for a wide variety of applications. Her current research focuses on the development of methods using LCMS/MS to investigate PFAS in various sources.