Mass spectrometry closes the gap between PFAS emissions and real-time detection

A new generation of mass spectrometry is enabling continuous, real-time detection of PFAS in air, closing a gap left by conventional sampling methods that can only confirm what has already passed through a stack or vent.

Most regulatory PFAS air methods, including the US Environmental Protection Agency's OTM-45, OTM-50 and forthcoming OTM-55, rely on collecting a sample and sending it for laboratory analysis.

This approach cannot detect short-lived process upsets between sampling windows, and results are typically available only after a delay of several weeks.

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A recent review in Nature Reviews Earth & Environment found that even incineration or pyrolysis processes reporting destruction efficiencies above 99.99% can still release measurable fluorinated by-products that a fixed target list may miss entirely.

Chemical ionisation mass spectrometry, typically paired with iodide reagent ions for PFAS-specific sensitivity, ionises an air stream directly and identifies compounds by mass in seconds, without sample preparation.

Detection limits in the parts-per-trillion range are achievable, allowing continuous, unattended operation.

Deployments over the past two years illustrate the range of applications.

At a Swiss municipal waste incineration plant, a two-week campaign sampling treated flue gas resolved short-chain PFAS, including trifluoroacetic acid, at concentrations in the tens of parts per trillion – below the resolution of conventional flue gas monitoring techniques such as FTIR.

In Denmark, a thermal desorption pilot at a former firefighter training ground tracked PFAS off-gassing in real time across a 90-day heating ramp from ambient temperature to 400°C.

Laboratory testing of polymer-based semiconductor process materials measured multiple PFAS species outgassing during elevated-temperature processing, at concentrations from sub-parts-per-trillion to around one part per billion.

Testing of consumer products, including nail polish and wall paint, found measurable off-gassing of fluorinated compounds even at room temperature.

ASTM's D8560-24 guide for indoor air PFAS measurement now recognises chemical ionisation mass spectrometry as a complement to sorbent-based sampling, particularly for capturing fast-moving emission events.

Sorbent methods retain lower detection limits for some compounds and remain the basis for most regulatory compliance work.