Revised δ34S reference values for IAEA sulfur isotope reference materials S-2 and S-3

Revised delta S-34 reference values with associated expanded uncertainties (95% confidence interval (C.I.)) are presented for the sulfur isotope reference materials IAEA-S-2 (22.62 +/- 0.16 parts per thousand) and IAEA-S-3 (-32.49 +/- 0.16 parts per thousand). These revised values are determined using two relative-difference measurement techniques, gas Source isotope ratio mass spectrometry (GIRMS) and double-spike multi-collector thermal ionization mass spectrometry (MC-TIMS). Gas analyses have traditionally been considered the most robust for relative isotopic difference measurements of sulfur. The double-spike MC-TIMS technique provides all independent method for value-assignment validation and produces revised values that are both unbiased and more precise than previous value assignments. Unbiased delta S-34 values are required to anchor the positive and negative end members Of the Sulfur delta (6) scale because they are the basis for reporting both delta S-34 values an-cl the derived mass-independent Delta S-33 and Delta S-36 Values. Published in 2009 by John Wiley & Sons, Ltd.