Standard mixtures of ambient volatile organic compounds in synthetic and whole air with stable reference values

Research into the role of volatile organic compounds (VOCs) in the chemistry of the lower atmosphere has led to requirements for stable and accurate standard gas mixtures to underpin long‐term monitoring of global background and polluted urban concentrations. We describe a novel method for the preparation of standard mixtures containing thirty compounds in matrices of nitrogen and whole air. The estimated uncertainty in the amount fractions of the compounds in these mixtures is typically 2% (relative) and typical stability is better than 0.2% per annum. We also report the results of a comparison exercise between eight laboratories using these mixtures, which indicate that typical uncertainties achievable by laboratories making measurements of these compounds are better than demonstrated previously.