Calibration with permeation devices: is there a pressure dependence of the permeation rates?

Permeation devices are often used for calibration purposes in atmospheric trace gas measurements. Compared to bottled gas standards, they have some advantages such as low cost, weight, and space requirements, and better long-term stability. For some devices, permeation rates have been reported to depend on pressure, and this dependence can lead to calibration errors in airborne experiments. The permeation rates of commercially available permeation devices for the compounds acetone, acetonitrile, and sulfur dioxide were checked for a pressure dependence by two independent tests. Their permeation rates were found to be independent of external pressure.