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TimestampEmail AddressStockCompanyLot #µmol 15NH4+/mol 15N2µmol 15NOx/mol 15N2Analyst (Name and Email)Preparation of nitrate and ammonium solutionsIsotopic analyses of ammonium and of nitrate + nitrite ReferencesCitation (include weblink if available)
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11/23/2018 7:00:09julie.granger@uconn.edu99%15N2
Cambridge Isotope Laboratories
I-167270.052 ± 0.0200.024 ± 0.005
Richard Dabundo (rcdabundo@gmail.com)
Aqueous solutions (40 mL) of natural abundance (unlabeled) ammonium and nitrate salts at a concentration of 5 µM were equilibrated overnight in a crimpled-sealed 60 mL glass serum vial with an air headspace supplemented with a 1.0 mL injection of 15N2 gas. Control solutions were treated similarly, but not supplemented with 15N2 gas. The 15N/14N ratio of ammonium was measured with the hypobromite-azide method (Zhang et al. 2007). Nitrate + nitrite (NOx) 15N/14N isotope ratios were measured with the denitrifier method (Sigman et al. 2001; Casciotti et al. 2002).
Casciotti, K. L., Sigman, D. M., Hastings, M. G., Böhlke, J. K., & Hilkert, A. (2002). Measurement of the oxygen isotopic composition of nitrate in seawater and freshwater using the denitrifier method. Analytical Chemistry, 74(19). https://doi.org/10.1021/ac020113w
Dabundo, R., Lehmann, M. F., Treibergs, L., Tobias, C. R., Altabet, M. A., Moisander, P. H., Granger, J. 2014. The contamination of commercial 15N2 gas stocks with 15N-labeled nitrate and ammonium and consequences for nitrogen fixation measurements. PLoS ONE 9(10): e110335. doi: 10.1371/journal.pone.01 01335
Sigman, D. M., Casciotti, K. L., Andreani, M., Barford, C., Galanter, M., & Böhlke, J. K. (2001). A bacterial method for the nitrogen isotopic analysis of nitrate in seawater and freshwater. Analytical Chemistry, 73(17). https://doi.org/10.1021/ac010088e
Zhang, L., Altabet, M. A., Wu, T., Hadas, O. (2007) Sensitive measurement of NH4+ 15N/14N (15NH4+) at natural abundance levels in fresh and saltwaters. Anal Chem 79(14): 5297-303.
Dabundo, R. & Granger, J. (2018). Measurements of 15N contaminants in Cambridge Isotopes 15N2 stock, lot# I-16727 [Database record]. Retrieved from The Ocean Carbon Biogeochemisry Database of 15N Contaminants in Commercial 15N2 Stocks. Weblink.
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