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International Comparison of a Hydrocarbon Gas Standard at the Picomol per Mol Level



George C. Rhoderick, David L. Duewer, Eric Apel, Annarita Baldan, Bradley Hall, Alice Harling, Detlev Helmig, Gwi S. Heo, Jacques Hueber, Mi E. Kim, Yong D. Kim, Benjamin Miller, Stephen Montzka, Daniel Reimer


Studies of climate change increasingly recognize the diverse influences of hydrocarbons in the atmosphere, including roles in particulates and ozone formation. Measurements of key non methane hydrocarbons (NMHCs) suggest atmospheric mole fractions ranging from low pmol/mol (ppt) to nmol/mol (ppb), depending on location and compound. To accurately establish mole fraction trends and to relate measurement records from many laboratories and researchers, it is essential to have good, stable, calibration standards. In February of 2008, the National Institute of Standards and Technology (NIST) developed and reported on pmol/mol standards containing 18 non methane hydrocarbon compounds covering the mole fraction range of 60 pmol/mol to 230 pmol/mol. The stability of these gas mixtures was only characterized over a short time period (2 3 months). NIST recently prepared a suite of primary standard gas mixtures by gravimetric dilution to ascertain the stability of the 2008 pmol/mol NMHC standards suite. The data from this recent chromatographic intercomparison of the 2008 suite to the 2011 suite confirms a much longer stability of almost 5 years for 15 of the 18 hydrocarbons. The agreement between the gravimetric values from preparation and the analytical mole fractions determined from regression illustrate the internal consistency of the suite within ± 2 pmol/mol. However, anomalous results for several of the compounds reflect stability problems for the three double-bonded hydrocarbons. An international intercomparison on one of the 2008 standards has also been completed. Participants included National Metrology Institutes, United States government laboratories and academic laboratories. In general results for this intercomparison agree to within about ±5 % with the gravimetric mole fractions of the hydrocarbons.
Analytical Chemistry


International Comparison, University Atmospheric Research Departments, National Metrology Institutes (NMIs), Non methane hydrocarbons (NMHCs), Primary Standard Mixture (PSM), Stability, Calibration techniques, Gas Chromatography, Compressed Gas Standard


Rhoderick, G. , Duewer, D. , Apel, E. , Baldan, A. , Hall, B. , Harling, A. , Helmig, D. , Heo, G. , Hueber, J. , Kim, M. , Kim, Y. , Miller, B. , Montzka, S. and Reimer, D. (2014), International Comparison of a Hydrocarbon Gas Standard at the Picomol per Mol Level, Analytical Chemistry, [online], (Accessed June 19, 2024)


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Created February 5, 2014, Updated September 28, 2020