VSMOW2 and SLAP2 are directly calibrated against the primary reference materials VSMOW and SLAP, establishing the highest level of metrological traceability for the realization of the VSMOW-SLAP stable isotope delta scales of oxygen and hydrogen.
VSMOW2 and SLAP2 were prepared at the IAEA Isotope Hydrology Laboratory following recommendations from a Consultants Group Meeting held by the IAEA in December 1996.
Certified values of VSMOW2
| Parameter | Certified value | Combined standard uncertainty (k=1) |
| δ(18O)VSMOW-SLAP(a) | 0.00 | 0.02 |
| δ(2H)VSMOW-SLAP(a) | 0.0 | 0.3 |
Information values of VSMOW2
| Parameter | Certified value | Combined standard uncertainty (k=1) |
| δ(17O)VSMOW-SLAP(a) | 0.00 | 0.02 |
(a) The expression of the quantity oxygen and hydrogen isotope delta follows Skrzypek et al.[1] Alternative expressions for the quantity, e.g. for oxygen, include δ(18O/16O) and more commonly δ18O following published guidelines.
Note: End users should state the values of reference materials used to normalize isotope data following the minimum requirements established by IUPAC [1].
References:
[1] SKRZYPEK, G. et al., Minimum requirements for publishing hydrogen, carbon, nitrogen, oxygen and sulfur stable-isotope delta results (IUPAC Technical Report), Pure Appl. Chem. 94 11–12 (2022) 1249.
