Urban VOC monitoring by VOCentinel at the Innsbruck Atmospheric Observatory (IAO)

Volatile Organic Compounds (VOCs), emitted by both biogenic and anthropogenic sources, play a crucial role in atmospheric processes and significantly affect air quality. Despite their importance, routine monitoring of VOCs poses challenges due to limitations in time-resolution, labor intensity, long-term stability, and compound-specific identification capabilities. Proton-transfer-reaction mass-spectrometry (PTR-MS) is widely used for detecting VOCs with high time-resolution and stability. However, as a soft chemical ionization method, it primarily identifies chemical compositions rather than specific compounds. Urban environments are especially challenging due to the release of thousands of VOCs from numerous sources, which can also necessitate additional corrections for possible interferences (Coggon et al., 2024; Peron et al., 2024). Acquiring additional chemical information through alternative ionization methods remains labor-intensive, making it impractical for long-term VOC monitoring.

The recently introduced VOCentinel (IONICON Analytik) leverages Selective-Reagent-Ion (SRI) PTR-MS combined with Automatic Measurement and Evaluation (AME), integrating recent technological advancements in PTR-MS, such as fast switching of reagent ions, extended volatility range (EVR, Piel et al., 2021) surface treatment, dynamic humidity control (Winkler et al., 2024), alongside IONICON's extensive experience in robust industrial monitoring. Essentially, five ionization modes sequentially ionize specific atmospheric VOCs within one minute, and the resulting mass spectra are immediately analyzed for chemical composition using a pattern matching algorithm.

The Innsbruck Atmospheric Observatory (IAO, Austria) is a well characterized urban field site (Karl et al., 2020) and hosts measurements within the Interreg Italy–Austria Breathing project, a collaboration between University of Innsbruck, ARPA Veneto, Ca’ Foscari University of Venice, and the Free University of Bolzano. A VOCentinel was installed in Summer 2025 at the Innsbruck Atmospheric Observatory (IAO, Austria) and has since then been monitoring urban VOC concentrations. In this presentation we will share first results from these multi-seasonal VOC measurements.

Coggon et al. (2024) Identifying and correcting interferences to PTR-ToF-MS measurements of isoprene and other urban volatile organic compounds, Atmos. Meas. Tech., 17, 801–825

Peron et al. (2024) Deciphering anthropogenic and biogenic contributions to selected non-methane volatile organic compound emissions in an urban area, Atmos. Chem. Phys., 24, 7063–7083

Piel et al. (2021) Introducing the extended volatility range proton-transfer-reaction mass spectrometer (EVR PTR-MS), Atmos. Meas. Tech., 14, 1355–1363.

Winkler et al. (2024) 100% humidity independent PTR-MS: Novel method and proof-of-concept, Phys. Scr. 99 121502

Karl et al. (2020) Studying Urban Climate and Air Quality in the Alps: The Innsbruck Atmospheric Observatory. Bull. Amer. Meteor. Soc., 101, E488–E507