Environmental Chamber Experiments

Fast and Flexible TOF Platform for Environmental Chamber Experiments

Background

Environmental Chamber Experiments

Environmental chambers and atmospheric simulation flow reactors are used to study the complex chemical reactions taking place in the atmosphere under well-controlled conditions. Such experiments have significantly improved our understanding of atmospheric chemical processes and the fate of many volatile organic compounds (VOCs) including anthropogenic pollutants. Fast and accurate measurement with limited fragmentation is required to capture and quantify the precursor species as well as their oxidation products. High mass resolving power of the analytical instrumentation enables the molecular identification of each product in the complex reaction mixture.

The TOFWERK API TOF is the gold standard for high-pressure chemical ionization. This flexible platform provides new types of reagent ion chemistry and complex experimental design. The Vocus PTR-TOF offers improved detection efficiency compared to conventional PTR instruments, allowing simultaneous, online monitoring of volatile hydrocarbons as well as a large number of oxygenated compounds and other semi-volatiles at trace concentrations. The versatility and fast-switching capability of the Vocus CI allows for more accurate and targeted analysis of highly functional molecules. Moreover, the newly developed aerosol inlet coupled to API TOF permits real-time and soft detection of compounds present in aerosol particles. These features simplify the design of experiments targeting chemical processes with fewer instruments.

For atmospheric chemistry research, please contact our partners at Aerodyne Research Inc.

Solutions

  • Real-Time VOC Analysis Using the Vocus PTR-TOF

    • Highest sensitivity available with sub-ppt limits of detection
    • High mass resolving power enables identification of individual compounds within complex mixtures
    • Real-time and fast data output capturing rapid changes in VOC concentrations
    • Specialized inlet design to minimize wall interactions
    • Full spectrum acquisition allows measurements of wide range of compounds simultaneously
    • No dependence on sample humidity
    • Custom Tofware analysis software enables robust and nuanced data interpretation

    What is PTR-MS?

    Environmental Chamber Experiments

    Volatile and semivolatile organic compounds were measured in the gas and particle phase by an iodide CIMS equipped with a FIGAERO interface during an environmental chamber study at MIT. The experiment explored the oxidation chemistry of trimethylbenzene over a 7 hour time period. The markers represent individual compounds, sized by their intensity in the mass spectrum and colored by their relative partitioning in the gas vs. particle phase.

  • Sensitive and Targeted Analysis Using the API- TOF Platform

    • High-pressure ion-molecule reactor for soft ionization of complex molecules
    • Flexible platform adapts to multiple types of reagent ion chemistry
    • Measure particle-phase compounds with add-on filter accessory
    • Automated switching between different measurement regimes
    • Custom Tofware analysis software enables robust and nuanced data interpretation

    Relevant Publications:

    1. Deming et al. Measurements of delays of gas-phase compounds in a wide variety of tubing materials due to gas–wall interactions. Atmos. Meas. Tech. 2019 https://doi.org/10.5194/amt-12-3453-2019
    2. Koss et al. Dimensionality-reduction techniques for complex mass spectrometric datasets: application to laboratory atmospheric organic oxidation experiments. Atmos. Chem. Phys., 2020 https://doi.org/10.5194/acp-20-1021-2020
    3. Schobesberger et al. Molecular understanding of atmospheric particle formation from sulfuric acid and large oxidized organic molecules.
    4. Isaacman-VanWertz et al. Chemical evolution of atmospheric organic carbon over multiple generations of oxidation. Nature Chem, 2018. https://doi.org/10.1038/s41557-018-0002-2
    5. Almeida et al. Molecular understanding of sulphuric acid–amine particle nucleation in the atmosphere. Nature, 2013.  https://doi.org/10.1038/nature12663
    6. Tröstl et al. The role of low-volatility organic compounds in initial particle growth in the atmosphere. Nature, 2016. https://doi.org/10.1038/nature18271
    7.  Riccobono et al. Oxidation Products of Biogenic Emissions Contribute to Nucleation of Atmospheric Particles. Science, 2014. https://science.sciencemag.org/content/344/6185/717

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