Effects of storage time and temperature on greenhouse gas samples in Exetainer vials with chlorobutyl septa caps

Measurement of greenhouse gas (GHG) flux using static chamber methods typically occurs immediately following sample collection. However, situations may arise requiring sample storage prior to analysis by gas chromatography. The objective of this study was to determine effects of storage time and temperature on carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) concentrations in vials containing "low" and "high" concentrations of certified standards. Samples were stored for 3, 7, 14, 28, and 84 days at four storage temperatures: room temperature, 25 °C, 4 °C, and -10 °C. Results indicated low and high concentration standards were not impacted by sample storage up to 28 days at any storage temperature. After 84 days, CO₂ concentrations were 0.6-14.4% lower than expected while CH₄ concentrations were up to 22% greater than expected. Results from future studies will allow for further refinement of scientifically supported guidance regarding appropriate storage temperature and time of GHG samples. •Few studies have examined impacts of storage time and temperature on GHG samples retained in traditional septa-capped vials.•Effects of storage time and temperature on GHG samples were examined.•Based on this study, GHG samples can be stored for up to 28 days at temperatures ranging from -10 °C to 25 °C.