title: Preparation and validation of fully synthetic standard gas mixtures with atmospheric isotopic composition for global CO2 and CH4 monitoring.
abstract: We report the preparation and validation of the first fully synthetic gaseous reference standards of CO2 and CH4 in a whole air matrix with an isotopic distribution matching that is in the ambient atmosphere. The mixtures are accurately representative of the ambient atmosphere and were prepared gravimetrically. The isotopic distribution of the CO2 was matched to the abundance in the ambient atmosphere by blending (12)C-enriched CO2 with (13)C-enriched CO2 in order to avoid measurement biases introduced by measurement instrumentation detecting only certain isotopologues. The reference standards developed here have been compared with standards developed by the National Institute of Standards and Technology and standards from the WMO scale. They demonstrate excellent comparability.
authors.affiliation: National Physical Laboratory, Analytical Science Division, Hampton Road, Teddington, Middlesex TW11 0LW, U.K.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Brewer
authors.forename: Richard J C
authors.initials: RJ
authors.lastname: Brown
authors.forename: Michael N
authors.initials: MN
authors.lastname: Miller
authors.forename: Marta Doval
authors.initials: MD
authors.lastname: Miñarro
authors.forename: Arul
authors.initials: A
authors.lastname: Murugan
authors.forename: Martin J T
authors.initials: MJ
authors.lastname: Milton
authors.forename: George C
authors.initials: GC
authors.lastname: Rhoderick
mesh_terms: D001272:Atmosphere / Q000737:chemistry*; D002245:Carbon Dioxide / Q000032:analysis* / Q000737:chemistry*; D060326:Chemistry Techniques, Synthetic; D004784:Environmental Monitoring / Q000592:standards*; D006112:Gravitation; D038622:Internationality; D007554:Isotopes; D008697:Methane / Q000032:analysis* / Q000737:chemistry*; D012015:Reference Standards; D015203:Reproducibility of Results; D035501:Uncertainty
chemical_list: D007554:Isotopes; D002245:Carbon Dioxide; D008697:Methane