PTFE-Chambers - Measurement of Volatiles and Reactive Gases

PTFE Gas & Volatile Flux Chambers. Experimentation on highly reactive molecules in the atmosphere requires specific chambers. Teflon chambers (PTFE Chambers) are often used for studies on volatiles and reactive gases because they are relatively chemically inert. PTFE-reaction chambers are thus ubiquitous in studies of atmospheric chemistry.

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.

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.