IAEA-616 is a certified reference material of pure CO2 providing the lowest reasonably achievable uncertainties for carbon and oxygen isotope delta measurements.
The intended use of IAEA-616, together with IAEA-615 and IAEA-617, is as calibrant in the determination of δ(13C)VPDB and δ(18O)VPDB-CO2 values in samples analysed by DI-IRMS, ensuring traceability to the VPDB and VPDB-CO2 isotope delta scales. It can also be used as calibrants of δ(13C)VPDB and δ(18O)VPDB-CO2 values in samples analysed by laser spectrometry like TILDAS, after dilution and by continuous flow (CF)-IRMS.
IAEA-616 is distributed in copper tubes of 6 mm outer diameter, containing approximately 70 µmol of CO2 gas.
Instructions for opening the copper tubes and connecting them to DI-IRMS are reported here: watch the video
Certified values of IAEA-616
| Parameter | Certified value | Combined standard uncertainty (k=1) |
| δ(13C)VPDB [‰] | -9.660 | 0.013 |
| δ(18O)VPDB-CO2 [‰] | -17.123 | 0.055 |
Note: For δ(13C), currently two scales exist and are in use: VPDB and VPDB-LSVEC. δ(13C) values reported on the VPDB and VPDB-LSVEC scale can differ, with maximum reported differences (VPDB minus VPDB-LSVEC) of +0.3 ‰ for materials with carbon isotope delta values around –45 ‰ and negligible difference (below current analytical combined uncertainty) at carbon isotope delta values close to zero [https://doi.org/10.1002/rcm.10018)].
End users should state the values of reference materials used to normalize isotope data following the minimum requirements established by IUPAC [DOI:10.1515/pac-2021-1108] and in the case of carbon, whether they are publishing δ(13C) values on the VPDB scale or the VPDB-LSVEC scale. Users should ensure that in one calibration they only use values for reference materials assigned on one scale.
