Implementing EPA OTM-50: TD-GC-MS/MS Analysis of Volatile PFAS in AirAir Monitoring, Methods, and Technology
Oral Presentation
Presented by P. Vaithee
Prepared by A. Fornadel1, T. Jeffers2, L. Mikaliunaite3, N. Shafer3, D. Cavagnino4, M. Bergna4
1 - Thermo Fisher Scientific, 104 Quinn Road, Severna Park, Maryland, 21146, United States
2 - Thermo Fisher Scientific, , Alachua, Florida, United States
3 - Markes International, , Sacramento, California, United States
4 - Thermo Fisher Scientific, , Milan, , Italy
Contact Information: [email protected]; 443-346-0728
ABSTRACT
The U.S. EPA Other Test Method 50 (OTM-50) provides guidance for monitoring volatile fluorinated compounds (VFCs) in air emissions, particularly those formed during incomplete destruction of per- and polyfluoroalkyl substances (PFAS). Reliable measurement of these volatile by-products is essential for evaluating destruction efficiency, environmental impact, and regulatory compliance. OTM-50 specifies canister-based air sampling followed by thermal desorption and GC–MS analysis; however, successful implementation requires careful optimization of analytical conditions to address the challenges associated with low-molecular-weight fluorinated compounds and complex emission matrices.
In this study, air samples collected in evacuated, passivated stainless-steel canisters according to OTM-50 guidance were analyzed using a Markes thermal desorption system coupled to a Thermo Scientific™ TSQ™ 9610 triple quadrupole GC-MS/MS. Separation was achieved by capillary gas chromatography, and detection was performed using multiple reaction monitoring (MRM) to enhance selectivity and sensitivity. Thermal desorption and MS/MS parameters were optimized to ensure efficient analyte transfer, robust chromatographic performance, and reliable quantitation under variable matrix conditions, including elevated CO₂ levels.
Preliminary results demonstrate effective detection and quantitation of target VFCs relevant to PFAS destruction processes. Compared to single-quadrupole MS, GC-MS/MS provided improved selectivity and reduced matrix interferences, with consistent retention times, reproducible responses, and sufficient sensitivity for low-level measurements anticipated in post-destruction air streams. The approach proved adaptable to varying emission compositions, mitigating quantitative bias associated with fluctuating backgrounds.
Overall, coupling a Markes TD system with the TSQ 9610 GC-MS/MS provides a practical and robust analytical workflow aligned with the objectives of EPA OTM-50, supporting laboratories and facilities engaged in PFAS air monitoring and method implementation.
