Three new reference materials were manufactured for calibration of relative stable nitrogen-isotope-ratio measurements: USGS25 (ammonium sulfate) d15N' = -30 per mil; USGS26 (ammonium sulfate) d15N' = +54 per mil; USGS32 (potassium nitrate) d15N' = +180 per mil, where d15N', relative to atmospheric nitrogen, is an approximate value subject to change following interlaboratory comparisons. These materials are isotopically homogeneous in aliquots at least as small as 10 µmol N2 (or about 1-2 mg of salt). The new reference materials greatly extend the range of d15N values of internationally distributed standards, and they allow normalization of d15N measurements over almost the full range of known natural isotope variation on Earth. The methods used to produce these materials may be adapted to produce homogeneous local laboratory standards for routine use.
|Title||New reference materials for nitrogen-isotope-ratio measurements|
|Authors||John K. Böhlke, C. J. Gwinn, T. B. Coplen|
|Publication Subtype||Journal Article|
|Series Title||Geostandards Newsletter|
|Record Source||USGS Publications Warehouse|
|USGS Organization||Toxic Substances Hydrology Program|