VOCentinel - a novel solution for automated real-time monitoring of atmospheric VOCs

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. Acquiring additional chemical information through alternative ionization methods remains labor-intensive, making it impractical for long-term VOC monitoring.

Here, we introduce an innovative solution to streamline these time-consuming tasks with the push of a button for key atmospheric VOCs. This new VOC monitor “VOCentinel” 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) surface treatment, active humidity control, and automatic pattern matching, 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. Automatic quality control ensures optimal instrument performance.

We will present a comprehensive characterization of the VOCentinel, emphasizing its long-term stability, and share initial results from VOC measurements in Innsbruck, Austria. Using isoprene as an example - an important biogenically emitted VOC often subject to chemical interferences in PTR-MS measurements - we demonstrate the system’s ability to automatically measure, evaluate, and correctly quantify compounds with isobaric and/or isomeric interferences.