USGS25

€150.00
Producing Laboratory: TERC
Availability: In stock
Ammonium Sulfate

​Reference material USGS25 is aimed at δ15N calibrations.

USGS25 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 (99.99% 14N; lot BI 1328) BI 1050) by dissolving and re-crystallizing a mixture of normal reagent salt and 15N depleted salt. The δ15N value of this reference material is the result of the statistical evaluation of interlaboratory comparisons [1,2].

Stable Isotope RatioReference V​alueStandard Uncertainty with k=1
δ15Nair(‰)-30.41​0.27

  1. References:
    1. BÖHLKE, J.K., GWINN, C.J., COPLEN, T.B., New reference materials for nitrogen isotope ratio measurements, Geostandards Newsletter 17 1 (1993) 159-164.
    2. 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.
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