Fractionation of sulfur isotopes in the preparation of sulfur dioxide. An improved technique for the precision analysis of stable sulfur isotopes

It is definitely shown that the main cause of error encountered in the precision isotope analysis of sulfur is in the isotope exchange reaction between SO2 and SO3 during the combustion process of SO2 preparation. The isotope fractionation factor between the two oxides is estimated to be 1.0035 at 1200°C. From this value, it is predicted that 3% fluctuation in the yield of SO2 would introduce uncertainty of 0.1‰ in the results of the ratio measurement. An improved combustion technique to maintain a constant yield of SO2 is described where pure oxygen is replaced by a nitroden-oxygen mixture (15: 1, v/v).