Indoor Air Analysis of Fluorotelomer Alcohols and Per- and Polyfluoroalkyl Substances

Significance of Topic

Per- and polyfluoroalkyl substances (PFAS) represent a growing environmental and public health concern. Fluorotelomer alcohols (FTOH) are precursors to persistent PFAS compounds and are widely used for their water- and oil-repellent properties. Their volatility allows them to partition into indoor air, leading to potential long-term human exposure even at low concentrations. Accurate monitoring of FTOH in indoor environments is essential for risk assessment and regulatory guidance.

Objectives and Study Overview

This work presents an analytical approach for quantifying four FTOH homologs (4:2, 6:2, 8:2, and 10:2) in indoor air. Key objectives included:

• Developing a cryogen-free thermal desorption (TD) GC/TQ method.
• Evaluating calibration performance and detection limits.
• Assessing recoveries and reproducibility across relevant concentration ranges.
• Demonstrating applicability to real-world indoor air samples from multiple indoor locations.

Methodology and Instrumentation

Air samples were collected for 24 hours at 40 mL/min onto PFAS-specific sorbent tubes using a low-flow pump. Thermal desorption was performed in splitless mode with helium at 300 °C for 3 minutes. Analytes were refocused on a cooled inlet at 10 °C and then transferred to a 60 m × 0.25 mm GC column. The GC oven ramped from 50 °C to 280 °C. Detection employed multiple reaction monitoring (MRM) on a triple-quadrupole MS, enhancing selectivity and sensitivity. Calibration standards covered 0.075–15 ng/tube, and recoveries were determined at three spike levels.

Used Instrumentation

• Agilent 8890 GC
• Agilent 7000E GC/TQ triple-quadrupole MS
• GERSTEL TD Core System for cryogen-free thermal desorption
• PFAS-specific TD 3.5+ sorbent tubes
• SKC Pocket Pump TOUCH for low-flow sampling

Main Results and Discussion

Calibration curves for the four FTOH compounds exhibited linear response across 0.075–15 ng/tube. Instrument detection limits ranged from 0.01 to 0.02 ng/tube. Recovery studies returned averages of 87.5–115.4% with relative standard deviations of 4.2–10.2%. Real-world indoor air sampling revealed:

• 6:2 FTOH detected in all six locations (3.47–16.5 ng/m3).
• 10:2 FTOH present in four locations (3.58–16.7 ng/m3).

MRM acquisition critically reduced background noise compared to full scan mode, enabling clear identification of low-abundance FTOH peaks in complex indoor air matrices.

Benefits and Practical Applications

The described TD-GC/TQ method offers:

• High selectivity via MRM, reducing interferences from co-eluting compounds.
• Low detection limits suitable for trace-level FTOH monitoring.
• Robust recoveries and reproducibility for quantitative analysis.
• Compatibility with large-volume, long-duration indoor air sampling protocols.

Future Trends and Potential Applications

Advancements may include optimized sorbent materials for broader PFAS capture, integration with high-resolution mass spectrometry for structural elucidation, and automated sampling workflows. Standardization of indoor PFAS monitoring protocols will support regulatory frameworks and health risk assessments. Emerging research may expand target lists to include emerging PFAS derivatives and their transformation products.

Conclusion

This study demonstrates that a cryogen-free TD-GC/TQ platform provides sensitive, reproducible, and selective analysis of FTOH in indoor air. The method’s performance and real-world applicability underscore its value for environmental monitoring and public health investigations related to PFAS exposure.

References

• Other Test Method 50 (OTM-50) Sampling and Analysis of Volatile Fluorinated Compounds from Stationary Sources Using Passivated Stainless-Steel Canisters. US EPA, 2024.