Ethylene loss from the gas phase of container‐seal systems

Ethylene losses from the gas phase of various container‐seal systems were studied to develop acceptable methods for containing ethylene during experiments. Ethylene at an initial amount of 104 μI I^‐1 was stored in glass vials at near atmospheric pressure for 20 h at 25–27°C and at 35% relative humidity external to the vials. Crimped serum vials sealed with saturated (NH₄)₂SO₄ solution, neoprene rubber septa, nitrile rubber (Hycar) septa, butyl rubber septa, and brown translucent silicone rubber septa lost ethylene at the rate of 1.8, 10.2, 16.2, 16.5, and 40.2 nl m^‐2s^‐1, respectively, over the 20‐h period. Screw‐capped reaction vials sealed with white silicone rubber septa lost ethylene at the rate of 30.2 nl m^‐2s^‐1. The (NH4)₂SO₄ solution was utilized as a seal by inverting a vial so that the salt solution covered the internal surface of the vial septum. Saturated (NH₄)²SO₄ solution is an effective seal. Silicone rubber should be avoided as a seal in systems for containing ethylene. Ethylene production values in the literature may be underestimates where silicone rubber seals have been used.