Analysis of PFAS Compounds in Indoor Air Using Thermal Desorption GC-MS Part 2: Using Tandem Mass Spectrometry to Improve Detectability and Improve Reliability

Polyfluoroalkyl Substances (PFAS) in the Environment
Oral Presentation

Prepared by K. Thaxton1, J. Stuff2, J. Whitecavage2, H. Hayes3, J. Miller4
1 - GERSTEL, 701 Digital Drive, Suite J, Baltimore, Maryland, 21090, United States
2 - GERSTEL Inc., 701 Digital Drive Suite J, Linthicum Heights, MD, 21090, United States
3 - Eurofins Air Toxics, 180 Blue Ravine Road, Suite B, Folsom, California, 95630, United States
4 - CAMSCO, 6732 Mayard Road, Houston, Texas, 77041, United States


Contact Information: kurt_thaxton@gerstel.com; 410-247-5885


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 last year’s presentation at NEMC, we introduced Thermal Desorption GC-MS as one possible way to address known issues when large volume air sampling is needed for either improved detectability or for time weighted average sampling. However, the use of single quadrupole MS was found to be problematic in terms of the surprisingly complex background of relatively ‘clean’ indoor air.

This presentation will show that the use of tandem mass spectrometry (MS/MS) is not only possible with “very volatile” PFAS species such as fluorotelomer alcohols (FTOH’s), but also greatly reduces the chemical background, resulting in the reduction of false positives and overall reduction in chemical noise, which in turn improves PFAS detectability. MS/MS method development will also be discussed, as well as examples of figures of merit for common PFAS compound classes of interest to the environmental community.