HELMHOLTZ-ZENTRUM FUER UMWELTFORSCHUNG GMBH -UFZ developed a versatile and compact reference gas generator for the calibration of ion mobility spectrometers or other gas detection technologies. The principle is based on the use of permeation tubes or diffusion vessels. This approach allows the reference gas to be generated with very low concentrations of analytes.
In contrast to most of the commercially available instruments, which dilute the complete permeation gas stream, we only used an aliquot for further dilution and the necessary quantity of inert gas can be considerably reduced. The permeation cell can be operated at elevated or reduced temperatures relative to ambient temperature. This temperature control allows the permeation rate to be adjusted depending on the volatility of the investigated substance and the membrane material used in the permeation tubes. As all connection lines and the mixing chamber after the permeation chamber are held at 70 °C, memory effects can be minimized. As a result, stable permeation rates can be rapidly achieved and the regeneration period after removing the substances from the permeation vessel significantly reduced. In this study, the analytical performance of the reference gas generator was validated using DMMP due to its importance for ion mobility measurements.