Monitoring Volatile PFAS in Air and Emissions by TD–GC–MS

Per- and polyfluoroalkyl substances (PFAS) are a large and diverse group of fluorinated compounds widely used in industrial processes and consumer products. Their chemical stability, which underpins their utility, also leads to environmental persistence and potential adverse effects on human health. As a result, PFAS are increasingly subject to regulatory scrutiny worldwide.

While much early attention focused on non-volatile PFAS in water and soil, there is growing recognition of the importance of volatile and semi-volatile PFAS in air. These compounds contribute to atmospheric transport, human exposure via inhalation, and the formation of more persistent species through environmental transformation. Fluorotelomer alcohols (FTOHs), for example, can degrade into perfluorinated carboxylic acids, including compounds of regulatory concern.

In parallel, efforts to remediate PFAS-contaminated materials have introduced new analytical challenges. Destruction technologies designed to mineralize PFAS can generate volatile fluorinated compounds (VFCs) as products of incomplete destruction, requiring careful monitoring to ensure environmental safety (Figure 1).

These developments have driven the creation of standardized methods targeting volatile PFAS across different contexts. Two notable examples are:

• US EPA OTM-50, for monitoring VFCs in industrial emissions;¹
• ASTM D8591, for measuring FTOHs emitted from products to interior environments.²

Both methods rely on thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS), highlighting its central role in addressing emerging regulatory needs.

What Are the Regulatory Drivers for Volatile PFAS Monitoring?

Regulatory frameworks for PFAS are evolving rapidly, with increasing emphasis on:

• Comprehensive life cycle assessment (source → emission → exposure);
• Control of industrial emissions and destruction processes;
• Improved understanding of airborne exposure pathways.

OTM-50 was developed to support the evaluation of PFAS destruction technologies by enabling the measurement of VFCs emitted from stationary sources. These compounds may be present at concentrations ranging from parts-per-billion by volume down to low parts-per-trillion levels, requiring highly sensitive analytical techniques (Figure 1).

ASTM D8591 addresses a complementary challenge: the quantification of FTOHs released from products into indoor environments. PFAS emissions from treated materials can adversely affect the occupants’ health, making reliable air monitoring essential for exposure assessment and regulatory compliance.

Together, these methods illustrate the increasing need for robust, standardized analytical workflows capable of handling diverse sample matrices and stringent quality requirements.

TD–GC–MS as a Platform for Volatile PFAS Analysis

TD–GC–MS combines efficient preconcentration with high-resolution separation and sensitive detection, making it well suited to trace-level analysis of volatile PFAS.

Key advantages include:

• Preconcentration without solvents, reducing contamination risks and improving reproducibility;
• Compatibility with a wide volatility range, from ultra-volatile gases to semi-volatile compounds;
• Flexibility in sampling approaches, including canisters and sorbent tubes;
• Integration with mass spectrometric detection, enabling selective and quantitative analysis.

Both OTM-50 and ASTM D8591 build on established TD–GC–MS workflows while introducing method-specific adaptations to address their respective analytical challenges.

Monitoring PFAS Destruction Products: OTM-50

OTM-50 is a performance-based method designed to quantify 30 volatile fluorinated compounds generated during PFAS destruction processes. Sampling is carried out using evacuated, passivated canisters, often combined with a conditioning train to remove water and acid gases prior to collection (Figure 2).

Following sampling, analytes are preconcentrated and analyzed by GC–MS. The method targets compounds across a wide volatility range, including ultra-volatile species such as tetrafluoromethane, requiring careful control of trapping and desorption conditions.

A key analytical challenge is the presence of matrix components such as water vapor and carbon dioxide, which can interfere with chromatographic performance and detector response. Effective water management and optimization of desorption conditions are therefore critical to maintaining data quality.

OTM-50 imposes rigorous quality control criteria, including:

• Multi-point calibration with strict accuracy requirements;
• Method detection limits in the low-ppt range;
• Laboratory blanks below defined thresholds;
• Precision criteria based on replicate analyses.

Reported method detection limits of approximately 10–30 ppt demonstrate that TD–GC–MS can meet the sensitivity requirements of the method (Figure 3).

The method also highlights the importance of monitoring products of incomplete destruction, as these compounds may pose environmental and health risks distinct from the parent PFAS.

Measuring Airborne PFAS: ASTM D8591

ASTM D8591 focuses on the determination of FTOHs in chamber air, typically collected onto sorbent tubes and analyzed by TD–GC–MS/MS. These compounds are of particular interest due to their role as precursors to persistent PFAS.

Compared with OTM-50, the analytical emphasis shifts from ultra-volatile gases to semi-volatile species, but similar challenges remain, including:

• Trace-level detection;
• Background contamination from laboratory materials;
• Complex and stringent quality control requirements.

The method specifies a detailed sequence of quality checks, including calibration, recovery checks, daily calibration verification, and internal audit procedures. Each step must meet defined acceptance criteria before sample analysis can proceed (Figure 4).

One of the most significant challenges is the ubiquitous presence of PFAS in laboratory environments, which can lead to background contamination. Demonstrating PFAS-free blanks is therefore essential for ensuring data integrity.

Despite these challenges, TD–GC–MS/MS provides:

• Strong linearity across calibration ranges;
• Detection limits in the low picogram range;
• Reliable quantitation of multiple target analytes.

These capabilities support the use of ASTM D8591 for exposure assessment, indoor air studies, and regulatory monitoring.

Future Perspectives

As PFAS regulations continue to evolve, analytical methods will need to adapt to:

• Expanding lists of target compounds;
• Lower regulatory limits;
• Increased demand for routine monitoring across multiple environments.

There is also growing interest in non-target and suspect screening approaches, which may require integration with high-resolution mass spectrometry. However, targeted TD–GC–MS methods remain essential for regulatory compliance due to their robustness, sensitivity, and standardization.

Automation and workflow optimization will play an increasingly important role in managing the complex quality control requirements associated with PFAS analysis, particularly for methods such as ASTM D8591.

Conclusions

The monitoring of volatile PFAS in air and industrial emissions is an increasingly important component of environmental and regulatory science. Standard methods such as US EPA OTM-50 and ASTM D8591 highlight the need for sensitive, reliable, and standardized analytical approaches.

TD–GC–MS provides a versatile platform capable of addressing these requirements across a range of compound classes and sample matrices. By combining efficient preconcentration with selective detection, it enables the measurement of PFAS and related compounds at trace levels while supporting stringent quality control protocols.

As regulatory frameworks continue to develop, TD–GC–MS is likely to remain a key tool for ensuring compliance and improving understanding of PFAS behavior in the environment.

References

1. US EPA OTM-50; https://markes.com/standard-methods/us-epa-other-test-method-otm-50 (accessed 2026-05-18).
2. ASTM D8591; https://www.astm.org/d8591-24.html (accessed 2026-05-18).