IAEA-CH-7

• Unit Size: 3.6 g
• Price per Unit: 200 EUR
• Report: n.a.
• Date of Release: 4/1/1987
• Reference Sheet: download (pdf)
• Contact point: Analytical-Reference-Materials.Contact-Point@iaea.org

​​​​International Chemical Safety Card (ICSC): ICSC_1488

IAEA-CH-7 is a secondary reference material. Its intended use is as calibrant when δ¹³C and δ²H are determined in organic materials using IRMS (Isotope Ratio Mass Spectrometry) coupled with an EA (Elemental Analyser) and Pyrolizer, for obtaining traceability of the data to the VPDB δ¹³C scale and VSMOW-SLAP δ²H scale, respectively.  

IAEA-CH-7 (formerly PEF-1) was prepared by H. Gerstenberger and M. Herrmann, Zentralinstitut für Isotopen- und Strahlenforschung, Leipzig, Germany [1].

Details about the characterization of IAEA-CH-7 are reported in [2] and [3].

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., 2025, RCM, Rapid Communications in Mass Spectrometry, 2025; 39:e10018 1 of 11 https://doi.org/10.1002/rcm.10018). 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[4] 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:

1. ​GERSTENBERGER, H., HERRMANN, M., Report on the intercomparison for the isotope standards Limestone KH2 and Polyethylene Foil PEF 1, ZfI-Mitteilungen 66 (1983) 67-83.
2. 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.
3. SCHIMMELMANN, A., QI H., COPLEN, T.B., BRANDT, W.A., FONG, J., MEIER-AUGENSTEIN, W., KEMP, H.F., TOMAN, B., ACKERMANN, A., ASSONOV, S., AERTS-BIJMA, A.T., BREICHA, R., CHIKARAISHI, Y., DARWISH, T., ELSNER, M., GEHRE, M., GEILMANN, H., GROENING, M., HELIE, J.F., HERRERO-MARTIN, S., MEIJER, H.A.J., SAUER, P.E., SESSION A.L., WERNEN R.A. Organic Reference Materials for Hydrogen, Carbon, and Nitrogen Stable Isotope-Ratio Measurements: Caffeines, n‑Alkanes, Fatty Acid Methyl Esters, Glycines, L‑Valines, Polyethylenes, and Oils. Anal. Chem. 88 (2016) 4294−4302 
4. 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.