IAEA-CH-6 is a secondary reference material. Its intended use is as calibrant when δ(13C) is determined in organic materials using IRMS (Isotope Ratio Mass Spectrometry) coupled with an EA (Elemental Analyser), for obtaining traceability of the data to the VPDB-LSVEC δ(13C) scale. IAEA-CH-6 (its former name was Sucrose ANU) was supplied to the IAEA by H. Polach, Australian National University, Canberra [1]. Details about the characterization of IAEA-CH-6 are reported in [2].
Parameter | Reference value | Combined standard uncertainty
with k=1 |
δ(13C)VPDB-LSVEC (‰) | -10.45 | 0.03 |
For δ(13C), currently two scales exist and are in use: VPDB (Vienna Peedee belemnite) and VPDB-LSVEC (lithium carbonate prepared by H.J. Svec), as acknowledged by experts during the 12th IAEA meeting held in Vienna, 22-26 January 2024 (Camin et al., 2024, RCM, under review). 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.
End users should state the values of reference materials used to normalize isotope data following the minimum requirements established by IUPAC[3] and 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.
References:
- HUT, G., Consultants' Group Meeting on Stable Isotope Reference Samples for Geochemical and Hydrological Investigations, Vienna, Austria, 16 - 18 September 1985. Report to the Director General, International Atomic Energy Agency, Vienna, Austria (1987).
- COPLEN, T.B., BRAND, W.A., GEHRE, M., GRÖNING, M., MEIJER, H.A.J., TOMAN, B., VERKOUTEREN, R.M., New guidelines for δ13C measurements, Anal. Chem. 78 (2006) 2439-2441.
- SKRZYPEK, G. et al., Minimum requirements for publishing hydrogen, carbon, nitrogen, oxygen and sulfur stable-isotope delta results (IUPAC Technical Report), Pure Appl. Chem. (2022) 1.
