STABILITY OF COMPRESSED GAS-MIXTURES CONTAINING LOW-LEVEL VOLATILE ORGANIC-COMPOUNDS IN ALUMINUM CYLINDERS

Compressed gas mixtures containing up to twenty-six volatile organic c ompounds (VOCs) in a balance of nitrogen have been prepared and analyz ed at the National Institute of Standards and Technology (NIST). The m ixtures are contained in aluminum cylinders and the hydrocarbons inclu ded are aromatic or aliphatic, both saturated and unsaturated and some containing a halogen, oxygen or nitrogen atom. The individual compoun ds are present at concentrations ranging from 0.1-3000 nmol/mol and th e relative standard uncertainty in the concentration of each is betwee n +/- 2-5%. The stability of the mixtures over various time intervals is discussed.