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.
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.
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:
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).
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.