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IAEA-31015N labelled urea Pure Substance

Reference material IAEA-310 consists of two materials (A and B) which were prepared from highly enriched 15N labelled urea by dilution with the unlabelled compound in redistilled water. After mixing, evaporation, freeze drying, crystallization and further mixing, the material was dispensed into glass vials. The values listed above were established on the basis of statistically valid results submitted by laboratories which had participated in an international intercomparison organized by the Section of Nutritional and Health Related Environmental Studies [1].

[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:

1. 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).