I have a low volume (~ 10 ml) vacuum system that seems to “soak in” and then slowly release CO2. For example, if we expose it to room air (~ 1000 ppm CO2), then pump out and even purge with nitrogen, once we close off the system, the concentration of CO2 starts at zero, but then slowly rises to well above 2000 ppm over 10’s of minutes. The operating pressure is pretty moderate at about 1 to 10 kpa. One suspect is the epoxy that we are using to seal components. Do you know if epoxy can preferentially hold on to and then outgas CO2? Another suspect is trapped gas in dead-end / virtual leak locations, in which the heavier CO2 molecules are preferentially trapped as compared to the lighter N2 molecules. Does this seem likely? Please offer any advice suggestions. Thanks.