Humidity Independent PTR-MS with Dynamic Humidity Control: Reliable Real-Time Monitoring

Humidity independent PTR-MS with Dynamic Humidity Control (DHC)

Reliable Real-Time Monitoring with PTR-MS Using Dynamic Humidity Control

Proton-Transfer-Reaction – Mass Spectrometry (PTR-MS) is well-known for its real-time quantification capability. However, variations in sample humidity can negatively impact the accurate quantification of certain distinct compounds. Traditional countermeasures, such as humidity-dependent calibrations, sample drying, or introducing excessive amounts of H₂O into the reaction region, only mitigate the problem and have considerable drawbacks. With the use of the IONICON Dynamic Humidity Control (DHC) technology we present a novel method that can eliminate interferences caused by varying sample humidity*. DHC offers a robust and practical solution for long-term environmental air monitoring, throughout changing weather conditions, for the analysis of various processes in food and flavor science, such as drying or fermentation, for industrial monitoring tasks, or simply for measuring gas standards at distinct humidification levels.

Humidity actively controlled in reaction region

Our innovative approach involves the controlled introduction of water vapor directly into the PTR reaction region. By continuously monitoring and regulating the humidity level – quantified through the water-cluster distribution – the reaction region is maintained at a constant humidity, irrespective of variations in the sample’s water content. This dynamic stabilization ensures that detected ion signals are independent of sample humidity, enabling accurate and reproducible quantification.

Advantages over traditional methods

Unlike conventional strategies, our humidity control approach offers several key advantages:

Elimination of Calibration Complexities: Humidity-dependent calibrations are no longer required, simplifying operation and improving measurement reliability.
Preservation of Sample Integrity: Unlike sample drying, this method better maintains the chemical composition of the sample, ensuring no loss or transformation of analytes.
Enhanced Practicality: The system can operate automatically and does not require excessive H₂O addition, avoiding issues such as altered reaction kinetics.

Fig.: Normalized ion yields measured for a constant concentration of H2S at different levels of Absolute sample Humidity (AH). With DHC (blue symbols) the H2S.H+ ion yield, and thus compound quantification, becomes completely independent of the sample humidity.

Conclusion

The novel DHC technology actively and dynamically controls the humidity of your IONICON PTR-MS. Signal intensities can now be decoupled from varying sample humidities, thereby directly enhancing the reliability and stability of the PTR-MS. This allows for an accurate and consistent quantification across diverse sampling conditions without any further labor-intensive characterizations. The dynamic humidity control addresses a long-standing challenge in broad fields of PTR-MS applications. These include virtually any specialized case where maintaining stable humidity in the ion-molecule reactor leads to more reliable data, such as in food and flavor science or air quality monitoring.

Discover the cornerstones of IONICON-Grade PTR-MS Technology and learn more about the essentials for ION Chemistry here.

*Source: K. Winkler, R. Gutmann, A. Mauracher, B. Rosenkranz, L. Märk, P. Sulzer,
100% humidity independent PTR-MS: Novel method and proof-of-concept. Physica Scripta 99/12 (2024) 121502 (10.1088/1402-4896/ad9362): https://doi.org/10.1088/1402-4896/ad9362