Measurements for per- and polyfluoroalkyl substances (PFAS) in air have expanded. There are few analytical methods available which measure PFAS in air. Thermal desorption, gas chromatography, and tandem mass spectrometry (TD-GC-MS/MS) is being successfully used for this purpose by the US EPA for the evaluation of indoor air and indoor materials using a simple, valve-free thermal desorber architecture.
Once the analytes are trapped on a thermal desorption tube, the tubes are desorbed and the analytes are refocused onto a concentrator trap. In the past, low temperatures were used (< -40 °C) to non-selectively trap and refocus PFAS analytes. This approach was particularly suited for the determination of unknown compounds (non-targeted analysis) since it removes the possibility of analyte interaction with the sorbent in the concentrator trap. Also, the use of low temperatures provided a drastic reduction in method development time since only one temperature and one type of trap is needed for all analyses.
A complete cryogen-free, valve-free method for determining FTOHs in indoor air has now been developed [4] and evaluated using samples taken from both commercial and residential locations. The method called “dynamic focussing” has excellent figures of merit and results in data that is reliable and simple to review. Small but measurable amounts of FTOHs in air were found at every location tested.