Methods for premixing gases in pressurized cylinders for use in controlled atmosphere experiments

Methods for mixing various concentrations of O 2 , CO 2 , N 2 , and C 2 H 4 in high-pressure cylinders are described. The concentrations are mixed by partial pressure or partial volume and then are verified by gas chromatography. The procedures generally allow for a precision of ±5% when either 1.0% O 2 or CO 2 or higher concentrations are mixed with N 2 or when C 2 H 4 at 100 μl.liter -1 , or more, is added. For lower concentrations, or when both O 2 and CO 2 are combined with N 2 , then the precision is ±10%