Nathaniel E Ostrom1, Hasand Gandhi1, Tyler B Coplen2, Sakae Toyoda3, J K Böhlke2, Willi A Brand4, Karen L Casciotti5, Jens Dyckmans6, Anette Giesemann7,8, Joachim Mohn9, Reinhard Well7,8, Longfei Yu9, Naohiro Yoshida3,10. 1. Department of Integrative Biology and DOE Great Lakes Bioenergy Research Institute, Michigan State University, East Lansing, MI, USA. 2. U.S. Geological Survey, 431 National Center, Reston, VA, USA. 3. Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Yokohama, 226-8502, Japan. 4. Beutenberg Campus, Max-Planck-Institute for Biogeochemistry, P.O. Box 100164, 07701, Jena, Germany. 5. Department of Earth System Science, Stanford University, Stanford, CA, USA. 6. Büsgen Institute, Georg-August, Centre for Stable Isotope Research and Analysis, Germany. 7. University Göttingen, Göttingen, Germany. 8. Thünen Institut of Climate-Smart Agriculture, Braunschweig, Germany. 9. Laboratory for Air Pollution & Environmental Technology, Empa, Überlandstr. 129, CH-8600, Dübendorf, Switzerland. 10. Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, 152-8550, Japan.
Abstract
RATIONALE: Despite a long history and growing interest in isotopic analyses of N2 O, there is a lack of isotopically characterized N2 O isotopic reference materials (standards) to enable normalization and reporting of isotope-delta values. Here we report the isotopic characterization of two pure N2 O gas reference materials, USGS51 and USGS52, which are now available for laboratory calibration (https://isotopes.usgs.gov/lab/referencematerials.html). METHODS: A total of 400 sealed borosilicate glass tubes of each N2 O reference gas were prepared from a single gas filling of a high vacuum line. We demonstrated isotopic homogeneity via dual-inlet isotope-ratio mass spectrometry. Isotopic analyses of these reference materials were obtained from eight laboratories to evaluate interlaboratory variation and provide preliminary isotopic characterization of their δ15 N, δ18 O, δ15 Nα , δ15 Nβ and site preference (SP ) values. RESULTS: The isotopic homogeneity of both USGS51 and USGS52 was demonstrated by one-sigma standard deviations associated with the determinations of their δ15 N, δ18 O, δ15 Nα , δ15 Nβ and SP values of 0.12 mUr or better. The one-sigma standard deviations of SP measurements of USGS51 and USGS52 reported by eight laboratories participating in the interlaboratory comparison were 1.27 and 1.78 mUr, respectively. CONCLUSIONS: The agreement of isotope-delta values obtained in the interlaboratory comparison was not sufficient to provide reliable accurate isotope measurement values for USGS51 and USGS52. We propose that provisional values for the isotopic composition of USGS51 and USGS52 determined at the Tokyo Institute of Technology can be adopted for normalizing and reporting sample data until further refinements are achieved through additional calibration efforts.
RATIONALE: Despite a long history and growing interest in isotopic analyses of N2 O, there is a lack of isotopically characterized N2 O isotopic reference materials (standards) to enable normalization and reporting of isotope-delta values. Here we report the isotopic characterization of two pure N2 O gas reference materials, USGS51 and USGS52, which are now available for laboratory calibration (https://isotopes.usgs.gov/lab/referencematerials.html). METHODS: A total of 400 sealed borosilicate glass tubes of each N2 O reference gas were prepared from a single gas filling of a high vacuum line. We demonstrated isotopic homogeneity via dual-inlet isotope-ratio mass spectrometry. Isotopic analyses of these reference materials were obtained from eight laboratories to evaluate interlaboratory variation and provide preliminary isotopic characterization of their δ15 N, δ18 O, δ15 Nα , δ15 Nβ and site preference (SP ) values. RESULTS: The isotopic homogeneity of both USGS51 and USGS52 was demonstrated by one-sigma standard deviations associated with the determinations of their δ15 N, δ18 O, δ15 Nα , δ15 Nβ and SP values of 0.12 mUr or better. The one-sigma standard deviations of SP measurements of USGS51 and USGS52 reported by eight laboratories participating in the interlaboratory comparison were 1.27 and 1.78 mUr, respectively. CONCLUSIONS: The agreement of isotope-delta values obtained in the interlaboratory comparison was not sufficient to provide reliable accurate isotope measurement values for USGS51 and USGS52. We propose that provisional values for the isotopic composition of USGS51 and USGS52 determined at the Tokyo Institute of Technology can be adopted for normalizing and reporting sample data until further refinements are achieved through additional calibration efforts.
Authors: Joachim Mohn; Christina Biasi; Samuel Bodé; Pascal Boeckx; Paul J Brewer; Sarah Eggleston; Heike Geilmann; Myriam Guillevic; Jan Kaiser; Kristýna Kantnerová; Heiko Moossen; Joanna Müller; Mayuko Nakagawa; Ruth Pearce; Isabell von Rein; David Steger; Sakae Toyoda; Wolfgang Wanek; Sarah K Wexler; Naohiro Yoshida; Longfei Yu Journal: Rapid Commun Mass Spectrom Date: 2022-07-15 Impact factor: 2.586