MASS-SPECTROMETER SYSTEM FOR IN-VIVO MONITORING OF GAS-EXCHANGE IN PLANTS

A membrane introduction mass spectrometer system for the measurement o f gases in plants is presented Membrane inlets are coupled to a quadru pole MS (0-300 PC, ATOMKI) via flexible capillaries and a two-way valv e system. At a certain time only one probe is connected to the QMS and all the others are pumped simultaneously under high vacuum conditions , Two diffusion pumps are installed for the QMS and the idle inlets, r espectively. The vacuum and valve systems as well as the OMS are compu ter controlled. The silicone rubber membrane probes are placed into th e plant or over the surface of it. In latest experiments gas exchange of a reed is investigated, having the probes in the culms, rhizomes an d in the soil. ion monitoring in eight channels and mass scans in a pr eset range are available. The time-function of intensities at differen t masses(typically O-2, CO2 Ar, N-2) are monitored and correlated with physical and chemical effects on the plant.