PTFE-Chambers - Measurement of Volatiles and Reactive Gases
PTFE Gas & Volatile Flux Chambers. Experimentation on highly reactive molecules in the athmosphere requires specific chambers. Teflon chambers (PTFE Chambers) are often used for studies on volatiles and reactive gases because they are relatively chemically inert and do not react with many substances. PTFE-reaction chambers are thus ubiquitous in studies of atmospheric chemistry. For example, urban air pollution is typically characterized by high concentrations of ozone. This ozone is produced by well-understood reactions between (biogenic) volatile organic compounds (BVOCs, VOCs) and hydroxyl radicals (OH) in the presence of nitrogen oxides (NOx). Volatiles (VOCs) are reactive substances in the atmosphere which have a strong impact on atmospheric chemistry. Biogenic volatile organic compound (BVOC) emissions constitute approximately 90% of global VOC emissions.
Teflon Chambers for Experimentation on Reactive Gases and Volatiles
TC-400 Teflon Flux Chamber. The environmental chamber TC-400 was designed to study interactions between Ozone, BVOC emissions and tree physiological status. The chamber was developed for the project UOZONE of the University of Natural Resources and Life Sciences Vienna (BOKU). In brief, all mounting and side parts in contact with the air inside the 40 l plant chamber / reaction chamber are made from Teflon (PTFE). Plants are housed in PET bags. While potential interaction between vapor and PTFE-chamber walls can lead to the underestimation of some compounds, particular for least volatile compounds, the extend of prior use has been reported not to affect the sorption behaviour of Teflon (Zhang et al. 2015) - making the use of Teflon repiration chambers the preferred choice. See below for an exemplary set-up as realized for Fitzky et al. (2021).
We build PTFE reaction chambers similar to the TC-400 or completely custom designs according to experimental needs. Please contact Vienna Scientific to discuss your PTFE flux chamber requirements.
PTFE-Chamber Configuration
The TC-400 chamber design is freely configurable to meet the needs of your planned experiments, in particular to meet your target plant size (crown volume) and measured compounds. For example, we can adjust at your request:
- diameter of the reaction chambers` PTFE bottom (standard: 400 mm), size / location of the plant insertion point (Teflon-coated rubber), and numbers of air outlets realized in the bottom plate,
- height of air inlet in chamber (standard: 500 mm), and location of air entry point(s) (standard: on top, with diffusor),
- height of the table (fixed height or adjustable), on wheels or legs, no table etc.
In general, an "inversed design", targeting e.g. BVOC emissions by roots and microbiomes, is conceivable. We are happy to discuss your bespoke Teflon chamber configuration needs in person - adapting it to successfully measure the reactive molecules of your choice. If required, we can source electric valves, mass flow controllers, activated C filters, and PTFE-tubing etc. for your experimental set-up. For example, an airtight stainless steel housing for an activated carbon filter (replaceable) was developed to reliably scrub the ambient air before entering the PTFE chambers for measurements (see below).
PTFE Chambers for Ozone and BVOC Measurements - Design Examples
Activated Charcoal Filter - Design Example
CHAMBERS FOR Measuring OTHER GAS FLUXES
See ecosystem and mesocosm respiration chambers for plant experiments measuring less reactive gases such as CO2 and O2.
SAMPLING AIR ALIQUOTS
Consider the AS-101 Sorbent Tube Sampler to automatically sample volatiles (e.g. monoterpenes), etc. from the PTFE chambers into sorbent tubes for subsequent "offline" laboratory analysis.
BVOC Chamber Set-up - Example
Setup of an experiment using the VSI TC-400 VOC chambers, as used by Fitzky et al. (2021), Frontiers in Plant Sciences.
Ambient air was flushed through a dehumidifier (32% RH) and the charcoal filter (see above for pictures) for providing close-to VOC-free air. The incoming air was entering each TC-400 chamber through an elevated inlet covered by Teflon tape. A mass flow controller was regulating the incoming air pressure. The PTFE-covered table of the TC-400 was dividable, allowing for tree stem insertion, and sealed with a PTFE-coated silicon stopper. A tree was inserted into measurement chambers, whereas a "control" chamber remained empty for parallel VOC background measurements. Up to four chambers were operated in parallel, with one always serving as "blank". A thermocouple (T) was installed at all chambers to monitor leaf / air temperature. A PET-bag was placed over the bottom plate and sealed. Two outlets in the bottom of the PTFE plates of each chamber were used as overflow and for gas analysis by the PTR-TOF-MS and CO2/H2O detector, respectively. See “Materials and Methods” for details, and Supplementary Figure 1 and above for images of the chamber in use.
RecEnt Publications using the VSI TC-400 PTFE Chamber Systems for ExperimentAtion on BVOC Emissions
- Fitzky, A. C., Peron, A., Kaser, L., Karl, T., Graus, M., Tholen, D., ... & Rewald, B. 2021. Diversity and interrelations among the constitutive VOC emission blends of four broad-leaved tree species at seedling stage. Frontiers in plant science, 12, 708711.
- Fitzky, A. C., Kaser, L., Peron, A., Karl, T., Graus, M., Tholen, D., ... & Sandén, H. 2023. Same, same, but different: Drought and salinity affect BVOC emission rate and alter blend composition of urban trees. Urban Forestry & Urban Greening, 80, 127842.
- Peron, A., Kaser, L., Fitzky, A.C., Graus, M., Halbwirth, H., Greiner, J. et al. 2020. Combined effects of ozone and drought stress on the emission of biogenic volatile organic compounds from Quercus robur L. Biogeosciences, 2020, 1-27. DOI: 10.5194/bg-2020-260
Selected reADINGs ON cHAMBERS USED FOR sTUDIES ON vOCS, BVOCS AND oZONE
- Lüpke, M., R. Steinbrecher, M. Leuchner, and A. Menzel. 2017. The Tree Drought Emission MONitor (Tree DEMON), an innovative system for assessing biogenic volatile organic compounds emission from plants. Plant Methods 13:14.
- Fitzky, A. C., Kaser, L., Peron, A., Karl, T., Graus, M., Tholen, D., ... & Sandén, H. 2023. Same, same, but different: Drought and salinity affect BVOC emission rate and alter blend composition of urban trees. Urban Forestry & Urban Greening, 80, 127842.
- Tanaka, P. L., D. T. Allen, and C. B. Mullins. 2003. An environmental chamber investigation of chlorine‐enhanced ozone formation in Houston, Texas. Journal of Geophysical Research: Atmospheres 108.
- Timkovsky, J., P. Gankema, R. Pierik, and R. Holzinger. 2014. A plant chamber system with downstream reaction chamber to study the effects of pollution on biogenic emissions. Environmental Science: Processes & Impacts 16:2301-2312.
- Peron, A., et al. 2020. Combined effects of ozone and drought stress on the emission of biogenic volatile organic compounds from Quercus robur L. Biogeosciences, 2020, 1-27. DOI: 10.5194/bg-2020-260
- Zhang, X., R. Schwantes, R. McVay, H. Lignell, M. Coggon, R. Flagan, and J. Seinfeld. 2015. Vapor wall deposition in Teflon chambers. Atmospheric Chemistry and Physics 15:4197-4214.