Volatile organic compounds (VOCs) at ambient concentrations in the atmosphere play an important role in the photochemical generation of ozone. EU Directive 2002/3/EC mandates countries within the EU to make measurements of the specific set of VOC ozone precursors involved in this comparison.
The standards used for the comparison will contain the following components, all at amount fractions within a nominal range between 1 and 10 nmol/mol:
ethane, ethylene (ethene), acetylene (ethyne ), propane, propene, n-butane, i-butane (2 methyl propane), 1-butene, trans-2-butene, cis-2-butene, 1,3-butadiene, n-pentane, i-pentane (2 methyl butane), 1-pentene, (trans) 2-pentene, isoprene (2 methyl 1,3-butadiene), n-hexane, i-hexane (2 methyl pentane), n-heptane, n-octane, i-octane (2,2,4-trimethylpentane), benzene, toluene, ethyl benzene, m-xylene, p-xylene, o-xylene, 1,2,4-trimethyl benzene, 1,2,3-trimethyl benzene, 1,3,5-trimethyl benzene.
Note: the comparison will require results to be reported for all of the above species except for m and p-xylene, which should be reported as a combined value. The nominal pressure of the standard will be 40 bar.
This comparison will be carried out in parallel to a comparison of the same species amongst members of the European Network of Air Quality Laboratories (AQUILA).
Final Report 2008-12-31
The comparison has been completed and the results are available in the KCDB.