Two materials (-40 and -400 ‰ 15N vs. air) were prepared from highly enriched 15N-labelled ammonium sulfate by dilution by the unlabelled compound in bidestilled water. After mixing, evaporation, freeze drying, crystallization and further mixing, the material was transferred to the IAEA in small vials containing approximately 100 mg each and stored at room temperature.
| Ampoule | Analyte | Value | Unit | 95% Confidence Interval. | R/I/C |
| A | 15N | 39.8 | ‰ vs Air | 39.3 - 40.3 | R |
| B | 15N | 375.3 | ‰ vs Air | 373.0 - 377.6 | R |
[1] The isotopic compositions are given in parts per thousand difference from isotope ratio standard atmospheric N2 (Air)
(N) Number of accepted laboratory means which were used to calculate the recommended or information values and their respective confidence intervals about the mean value
(R/I) Classification assigned to the property value for analyte (Recommended/Information)
References:
- PARR, R.M., CLEMENTS, S.A., Intercomparison of enriched stable isotope reference materials for medical and biological studies. IAEA Report NAHRES-5, INTERNATIONAL ATOMIC ENERGY AGENCY, Vienna, Austria (1991).
