EURAMET 886 comparison of multicomponent ambient VOC measurements - Final report.

NPL prepared, analysed and circulated gas cylinders containing mixtures of Volatile Organic Compounds (VOCs) at amount fractions of a few nmol/mol (molar ppb). The set of VOCs was the set of ozone precursors listed in the Ambient Ozone Directive 2002/3/EC Annex VI. This Report describes all activities involved in delivering this comparison including measurement of cylinder stability. During this exercise the stability trial of 1-10 nmol/mol VOC mixtures showed less than 0.6% drift for most species over 1 year. Further work, providing increasing statistical weight, has shown less than 0.3% annual drift for all species over 2 years. The accuracy of these standards was further strengthened by the comparison results, which showed good agreement between participants preparing independent standards for the exercise (KRISS, NIST and NMi).