Organic Reference Materials for Hydrogen, Carbon, and Nitrogen Stable Isotope-Ratio Measurements: Caffeines, n-Alkanes, Fatty Acid Methyl Esters, Glycines, L-Valines, Polyethylenes, and Oils

An international project developed, quality-tested, and determined isotope−δ values of 19 new organic reference materials (RMs) for hydrogen, carbon, and nitrogen stable isotope-ratio measurements, in addition to analyzing pre-existing RMs NBS 22 (oil), IAEA-CH-7 (polyethylene foil), and IAEA-600 (caffeine). These new RMs enable users to normalize measurements of samples to isotope−δ scales. The RMs span a range of δ^2H_(VSMOW-SLAP) values from −210.8 to +397.0 mUr or ‰, for δ^(13)C_(VPDB-LSVEC) from −40.81 to +0.49 mUr and for δ^(15)N_(Air) from −5.21 to +61.53 mUr. Many of the new RMs are amenable to gas and liquid chromatography. The RMs include triads of isotopically contrasting caffeines, C_(16) n-alkanes, n-C_(20)-fatty acid methyl esters (FAMEs), glycines, and L-valines, together with polyethylene powder and string, one n-C_(17)-FAME, a vacuum oil (NBS 22a) to replace NBS 22 oil, and a ^2H-enriched vacuum oil. A total of 11 laboratories from 7 countries used multiple analytical approaches and instrumentation for 2-point isotopic normalization against international primary measurement standards. The use of reference waters in silver tubes allowed direct normalization of δ2H values of organic materials against isotopic reference waters following the principle of identical treatment. Bayesian statistical analysis yielded the mean values reported here. New RMs are numbered from USGS61 through USGS78, in addition to NBS 22a. Because of exchangeable hydrogen, amino acid RMs currently are recommended only for carbon- and nitrogen-isotope measurements. Some amino acids contain ^(13)C and carbon-bound organic ^2H-enrichments at different molecular sites to provide RMs for potential site-specific isotopic analysis in future studies

A System for High-quality CO2 Isotope Analyses of Air Samples Collected by the CARIBIC Airbus A340-600

In 2006 JRC-IRMM started CO2 isotope analyses on air sample collected by aircraft, the project CARIBIC. This application-CO2 isotope analyses for environmental monitoring requires upmost data quality. Only a few laboratories worldwide take part in the challenge to reach data quality targets required. Thereafter publishing details on the method, instruments and tests is mandatory and that was requested by the customer institute. In 2007 instruments for CO2 extraction followed by isotope analysis were installed at IRMM and critically tested, parameters optimised. Manuscript describes the results of tests, calibration approach, error budget as well as potential problems. Recommendations concerning operation of a similar system are given.JRC.D.4-Isotope measurement

Constraints on the flux of meteoritic and cometary water on the Moon from volatile element (N-Ar) analyses of single lunar soil grains, Luna 24 core

International audienceWe report new nitrogen and argon isotope and abundance results for single breccia clasts and agglutinates from four different sections of the Luna 24 drill core in order to re-evaluate the provenance of N trapped in lunar regolith, and to place limits on the flux of planetary material to the Moon’s surface. Single Luna 24 grains with 40Ar/36Ar ratios 15N values between -54.5‰ and +123.3‰ relative to terrestrial atmosphere. Thus, low-antiquity lunar soils record both positive and negative δ15N signatures, and the secular increase of the δ15N value previously postulated by Kerridge (Kerridge, J.F. [1975]. Science 188(4184), 162-164. doi:10.1126/science.188.4184.162) is no longer apparent when the Luna and Apollo data are combined. Instead, the N isotope signatures, corrected for cosmogenic 15N, are consistent with binary mixing between isotopically light solar wind (SW) N and a planetary N component with a δ15N value of +100‰ to +160‰. The lower δ15N values of Luna 24 grains compared to Apollo samples reflect a higher relative proportion of solar N, resulting from the higher SW fluence in the region of Mare Crisium compared to the central near side of the Moon. Carbonaceous chondrite-like micro-impactors match well the required isotope characteristics of the non-solar N component trapped in low-antiquity lunar regolith. In contrast, a possible cometary contribution to the non-solar N flux is constrained to be ⩽3-13%. Based on the mixing ratio of SW to planetary N obtained for recently exposed lunar soils, we estimate the flux of micro-impactors to be (2.2-5.7) × 103 tons yr-1 at the surface of the Moon. Our estimate for Luna 24 agrees well with that for young Apollo regolith, indicating that the supply of planetary material does not depend on lunar location. Thus, the continuous influx of water-bearing cosmic dust may have represented an important source of water for the lunar surface over the past ∼1 Ga, provided that water removal rates (i.e., by meteorite impacts, photodissociation, and sputtering) do not exceed accumulation rates

Correction for the 17O Interference in delta(13C) Measurements When Analyzing CO2 with Stable Isotope Mass Spectrometry (IUPAC Technical Report)

Measurements of delta (13C) determined on CO2 with an isotope-ratio mass spectrometer (IRMS) must be corrected for the amount of 17O in the CO2. For data consistency, this must be done using identical methods by different laboratories. This report aims at unifying data treatment for CO2 IRMS by proposing (i) a unified set of numerical values, and (ii) a unified correction algorithm, based on a simple, linear approximation formula. Because the oxygen of natural CO2 is derived mostly from the global water pool, it is recommended that a value of 0.528 be employed for the factor lambda, which relates differences in 17O and 18O abundances. With the currently accepted N(13C)/N(12C) of 0.011180(28) in VPDB (Vienna Peedee belemnite) reevaluation of data yields a value of 0.000 393(1) for the oxygen isotope ratio N(17O)/N(16O) of the evolved CO2. The ratio of these quantities, a ratio of isotope ratios, is essential for the 17O abundance correction: [N(17O)/N(16O)]/[N(13C)/N(12C)] = 0.035 16(8). The equation [delta (13C) asymp. 45delta VPDB-CO2 + 2 17R/13R (45delta VPDB-CO2 - lambda46delta VPDB-CO2)] closely approximates delta (13C) values with less than 0.010 promille deviation for normal oxygenbearing materials and no more than 0.026 promille in extreme cases. Other materials containing oxygen of non-mass-dependent isotope composition require a more specific data treatment. A similar linear approximation is also suggested for delta (18O). The linear approximations are easy to implement in a data spreadsheet, and also help in generating a simplified uncertainty budget.JRC.D.3-Knowledge Transfer and Standards for Securit

CO2 Isotopic Composition in the Upper Troposphere: the Project CARIBIC

Manuscript describes the project CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) and its approach of air sampling and CO2 isotope measurements by using a commercial aircraft (flights at ~ 10 km) as observational platform. In particular the paper focuses on possible sampling artefacts, on the troposphere-stratosphere mixing, effects which can specifically modify CO2 isotope composition and gives examples of CO2 isotope composition in the upper troposphere. The results to be presented in the manuscript have been obtained earlier, by measurements done at the Max Planck Institute for Chemistry, Mainz, Germany.JRC.D.4-Isotope measurement

Triple oxygen isotope systematics of structurally bonded water in gypsum

International audienc