Research and Field Campaigns


Description of our PTR-MS apparatus:

Graphics: Michael Schwarzmann (klick to enlarge)

hollow cathode drift tube quadrupole mass analyzer secondary electron multiplier   

A proton transfer reaction mass spectrometer (PTR-MS) system allows for on-line measurements of trace components with concentrations as low as a few pptv. The method is based on reactions of H3O+ ions produced in the hollow cathode (red), which perform non-dissociative proton transfer to most of the common volatile organic compounds (VOCs) but do not react with the major components present in clean air. These reactions take place in the drift tube (blue).
The focus of our group is on on-line monitoring of the diurnal variations of VOCs in the troposphere. Data obtained in field campaigns und laboratory experiments demonstrate the present sensitivity of PTR-MS to be in the range of a few pptv.
Besides medical applications by means of breath analysis, which allow for monitoring of metabolic processes in the human body, and especially food research are common applications of the PTR-MS


A great variety of laboratory experiments can also be performed by the use of the Selected Ion Flow Drift Tube (SIFDT), which is built up similarily - however on a bigger scale and with a second quadrupole mass selector at the front end of the apparatus: