Volatile PFAS Analysis in Whole Air Using a Cryogenic Preconcentrator and GC/TQPer- and Polyfluoroalkyl Substances (PFAS) in the Environment
Oral Presentation
Prepared by E. Fausett1, D. Cardin2, T. Robinson2, V. Vogel2, E. Park1
1 - Agilent Technologies, 2850 Centerville Rd, 2850 Centerville Rd, Wilmington, Delaware, 19808-1610, United States
2 - Entech Instruments, 2207 Agate Court, Simi Valley, Ca, 93065, United States
Contact Information: [email protected]; 435-830-2901
ABSTRACT
OTM 50 is a draft U.S. EPA method designed to identify and quantify volatile fluorinated compounds (VFCs). This work demonstrates full analysis of all 30 listed VFCs, spanning ultra volatile species such as CF₄ through more complex fluorinated organics. An Agilent 8890 GC coupled to both 7000E and 7010C triple quadrupole GC/MS systems was used, integrated with an Entech 7200A PFAS preconcentrator and SkyCan canister autosampler.
A GS GasPro column (60 m × 0.32 mm) was selected for its ability to separate VFCs at cryogenic temperatures. The GC was equipped with a modified LN₂ cooling port, enabling rapid cryogenic oven cooling. A heart cut approach was implemented to minimize CO₂ interference, and liquid nitrogen traps in the preconcentrator supported fast cooldown and high throughput operation. A Heavy Organics Guardian (HOG) pre column transfer line protected the GasPro column from contamination.
Detection was performed using Multiple Reaction Monitoring (MRM) to differentiate PFAS analytes from co eluting matrix components. For analytes too small to support multiple transitions, SIM ions were used. Seventy four transitions were incorporated into a dynamic MRM (dMRM) method, enabling confident identification of all 30 analytes and one internal standard. dMRM provided clear separation of compounds with similar retention times, including 1 H perfluoropentane, 1H nonafluorobutane, and several closely eluting C2–C3 fluorocarbons. Octafluorocyclobutane remained challenging due to shared transitions but was resolved chromatographically through optimized temperature programming.
A five point calibration (10–200 cc) of a 10 ppb standard mixture produced R² values >0.99 for all analytes, with 26 compounds fitting linear models and four requiring quadratic fits. Measured concentrations were within 20 % of theoretical values across all levels.
This method enables single run quantification of all OTM 50 VFCs, including ultra volatile species such as CF₄, using a cryogenic pre concentration GC/TQ workflow.
