Verification of certified sulphur values in steel reference materials by isotope-dilution mass spectrometry, and characterization of sulphur present on the solid samples

Sulphur in a number of steel reference materials has been determined by isotope-dilution mass spectrometry, utilizing both open-beaker and sealed-tube dissolution techniques. It is confirmed that the sulphur present in most samples can be completely converted into sulphate by the conventional open-beaker dissolution technique. The results on reference materials are in good agreement with the certified values for BCS samples and the recent or revised certified values for JSS and NBS samples. It is found that the sulphur concentration in the vicinity of the surface of the sample chips is higher than the average and that a significant amount of elemental sulphur is present on most chip samples. The ratio of elemental sulphur to average sulphur content tends to vary in proportion to the manganese content when this is less than 1%.