Reference material USGS26 is aimed at δ15N calibrations.
USGS26 is a dried salt of ammonium sulfate [(NH4)2 SO4]) which was prepared in 1992 by J. K. Böhlke, U.S. Geological Survey [1]. The material was prepared from Fisher ammonium sulfate (A938-500, lot # 915021) and Cambridge Isotopes ammonium sulfate (10% 15N; lot BI 1050) by dissolving and re-crystallizing a mixture of normal reagent salt and 15N enriched salt. The δ15N value of this reference material is the result of the statistical evaluation of interlaboratory comparisons [1,2].
Stable Isotope Ratio | Reference Value | Standard Uncertainty with k=1 |
δ15Nair(‰) | +53.75 | 0.24 |
References:
- BÖHLKE, J.K., GWINN, C.J., COPLEN, T.B., New reference materials for nitrogen isotope ratio measurements, Geostandards Newsletter 17 1 (1993) 159-164.
- BÖHLKE, J.K., COPLEN, T.B., "Interlaboratory comparison of reference materials for nitrogen-isotope-ratio measurements", Proceedings of a consultants' meeting held in Vienna, 1 - 3. Dec. 1993, IAEA-TECDOC-825, IAEA, Vienna, Austria (1995) 51-66.