Proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS)

What reactions take place in indoor areas and what reaction products are thereby formed? In which ways are humans exposed to air pollutants in the indoor environment? At the Fraunhofer WKI, we investigate complex chemical processes in indoor air and conduct research into human exposure to airborne compounds in relation to environmental influences, building and furnishing products, clothing and body-care products as well as personal consumption habits. With the “Proton-transfer-reaction time-of-flight mass spectrometer” (PTR-TOF-MS), we are able to perform measurements with great precision and high temporal resolution.

The largest group of air pollutants detectable in indoor air is that of the so-called volatile organic compounds (VOCs). These are usually collected through discontinuous sampling on a solid adsorber (Tenax^® TA) and analyzed in the laboratory by means of coupled gas chromatography/mass spectrometry following thermodesorption (TDS-GC/MS).

A proton-transfer-reaction mass spectrometer (PTR-MS) is a mobile online mass spectrometer that allows simultaneous real-time monitoring of hundreds of VOCs at very low concentrations, without the necessity of a prior sample preparation. At the Fraunhofer WKI, a proton-transfer-reaction mass spectrometer with integrated quadrupole mass filter (PTR-QMS) is available for this purpose.

In addition, the Fraunhofer WKI has a proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS), which, compared to the PTR-QMS, enables the analysis of a total mass spectrum within a fraction of a second - with high precision and at a significantly higher mass resolution. This allows, for example, the high-accuracy resolution of degradation or oxidation processes of chemical substances that occur in indoor air over very short periods of time.

• Model: PTR-TOF 4000 (IONICON Analytik GmbH)
• LoD < 5 pptv
• Sensitivity > 6000 cps/ppbv
• Resolution > 4000 m/Δm
• Response time < 100 ms