Analysis of PFAS Compounds in Indoor Air using Thermal Desorption GC-MS Part 3: Improvements for High Volume Sampling and Preconcentration of Volatile PFAS Species

Polyfluoroalkyl Substances (PFAS) in the Environment (Session 2)
Oral Presentation

Prepared by K. Thaxton1, J. Stuff2, J. Miller3
1 - GERSTEL GmbH, 1 Eberhard Gerstel Platz, Muelheim an der Ruhr, -- Please Select --, 45473, Germany
2 - GERSTEL Inc., 701 Digital Drive Suite J, Linthicum Heights, MD, 21090, United States
3 - CAMSCO, 6732 Mayard Road, Houston, Texas, 77041, United States


Contact Information: [email protected]; +14438334458

ABSTRACT

The fate of PFAS in air, both in the outdoor and indoor environments, is relatively unknown and is now becoming a new area of concern. Current PFAS measurement techniques involve capturing PFAS onto XAD or similar resins and extracting them with solvents; the extracts are then run in a way similar to those in drinking water. However, the analysis of extracts results in relatively poor analysis sensitivity due to the loss of analytes in the bulk of the un-analyzed extract.

In our previous two presentations, we described the use of thermal desorption, gas chromatography, and tandem mass spectrometry (TD-GC-MS/MS) as means to perform demanding PFAS in air work where the matrix is challenging due to high volume sampling, or due to issues with a complex environmental matrix, such as those often seen in soil vapor intrusion work.

In this presentation we will return to issues surrounding high volume sampling and preconcentration (pre-column focusing). In regards to high volume (>100 L) air sampling, we will cover the latest research in sorbent selection and sampling parameters used to both minimize breakthrough and handle large amounts of matrix, including water.

Next, once samples are trapped on TD tubes, those tubes are desorbed and the contents refocused onto a concentrator trap. Previously we used low temperatures (< -40 °C) to non-selectively trap and refocus PFAS analytes. This approach is particularly adept for non-targeted work where the sorbent choices in the concentrator trap may color the outcome of the non-targeted analysis, and also the use of low temperatures eliminated the need for method development around the choice of sorbents in the concentrator, allowing for a drastic reduction in method development time.

However, as time has progressed, some targeted volatile PFAS species, such as FTOH’s, have been identified as targets of particular concern, allowing for a new focus on targeted, high throughput analyses. The change from non-targeted to targeted approaches allows for a change in preconcentration strategy. We will now discuss sorbent/substrate choices for PFAS preconcentration as well as recent breakthroughs in preconcentration techniques and technology, and how these make reliable and durable analysis of PFAS in challenging matrices possible.