Sulphur isotope data consistency improved

The standard used for reporting relative sulphur isotope-abundance data has, historically, been troilite (FeS) derived from the Cañon Diablo meteorite, CDT. However, the isotopic inhomogeneity of this material - the variability in its sulphur-34/sulphur-32 isotope ratio is at least 0.4‰ - greatly exceeds the achievable analytical uncertainty of 0.05‰ (ref. 1). Accordingly, the International Union of Pure and Applied Chemistry (IUPAC) has recommended the setting up of a VCDT scale, which is expected to improve agreement between laboratories in measuring this ratio, δ³⁴S.