5.6. Evolving issues
It may not be possible to obtain certified standard gases because of their cost, or because it
takes too much time to import them from abroad by ship (air transportation is often
prohibited). If evacuated glass vials are used, it may be possible to store the collected gas
samples for a long time (up to 1–2 months). However, a chronic inability to obtain standard
gases cannot be solved by long-term storage. Here we discuss two possible stopgap
measures.