A new test gas generator for atmospheric trace compounds

A new device for generating atmospheric trace gases for calibration purposes is described, which allows to adjust test gas concentrations with fast response times and constant carrier gas flow. It consists of a permeation tubing surrounded by a solution of the substance of interest. Inside of the tubing a movable piston is placed. The position of this piston determines the available fraction of the permeation surface and hence the output of the test gas source. The device has been tested for the trace gas production of SO₂ and formaldehyde in the ppbv range. It shows linear dependence of the produced concentrations on the position of the piston, fast response times and good reproducibilities.Dedicated to Professor Dr. Dieter Klockow on the occasion of his 60th birthday