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    Nitrogen Isotope Materials

    Atmospheric N2 is isotopically homogeneous within current analytical uncertainty, and it is the international measurement standard for δ15N measurements, and is assigned a δ15N value of zero by international agreement.

    δ15N Values of Reference Materials

    Name NIST RM Material δ15NAir-N2
    Air N2air 0 ‰ *
    NSVEC8552nitrogen gas−2.78(4) ‰
    NBS 14nitrogen gas−1.18 ‰
    IAEA-N-18547ammonium sulfate+0.43(7) ‰
    IAEA-N-28548ammonium sulfateca. +20.35 ‰ **
    IAEA-NO-38549KNO3ca. +4 ‰ **
    USGS258550ammonium sulfateca. −30.3 ‰ **
    USGS268551ammonium sulfateca. +53.7 ‰ **
    USGS328558KNO3+180 ‰ 
    USGS348568KNO3−1.8(1) ‰ 
    USGS358569NaNO3+2.7(1) ‰ 
    USGS408573L-glutamic acid−4.52(6) ‰ 
    USGS418574L-glutamic acid+47.57(10) ‰ 
    USGS42human hair (Tibetan)+8.05(10) ‰ 
    USGS43human hair (Indian)+8.44(10) ‰ 
    IAEA-600caffeine+0.91(9) ‰ 
    IAEA-305Aammonium sulfate+39.79(1.09) ‰
    IAEA-305Bammonium sulfate+375.3(5.6) ‰
    IAEA-310Aurea+47.24(3.00) ‰
    IAEA-310Burea+244.63(1.73) ‰
    IAEA-311ammonium sulfate+4693(110) ‰
    Name NIST RM Material δ15NAir-N2

    Footnotes      Back to Top
    * Exact value defining the δ15NAir-N2 scale.
    ** See the Assessment of international reference materials for isotope-ratio analysis for more details.
    Values in parenthesis are expanded (k = 2) uncertainties applicable to the last digits. The values listed in this table are compilation and are not necessarily CIAAW recommendations.

    Citation

    W.A. Brand et al
    Assessment of international reference materials for isotope-ratio analysis Pure and Applied Chemistry 86, 425-467 (2014)