Stability of compressed gas mixtures containing low level volatile organic compounds in aluminum cylinders

Compressed gas mixtures containing up to twenty-six volatile organic compounds (VOCs) in a balance of nitrogen have been prepared and analyzed at the National Institute of Standards and Technology (NIST). The mixtures are contained in aluminum cylinders and the hydrocarbons included are aromatic or aliphatic, both saturated and unsaturated and some containing a halogen, oxygen or nitrogen atom. The individual compounds are present at concentrations ranging from 0.1–3000 nmol/mol and the relative standard uncertainty in the concentration of each is between ±2–5%. The stability of the mixtures over various time intervals is discussed.