Determination of sulfur in nickel-base alloys and alloy steels by isotope dilution mass spectrometry

An isotope dilution mass spectrometric method has been developed for the precise determination of 3–300 p.p.m. of sulfur in nickel-base alloys and alloy steels. The sample is dissolved in mixed acids, a spike is added, and nitrate ions are removed. Sulfate is reduced with a mixture of hydriodic, hypophosphorous, and hydrochloric acids; the hydrogen sulfide evolved is absorbed in cadmium acetate solution and converted to silver sulfide, which is burned to sulfur dioxide, for the isotope analysis. The relative standard deviation at the 50-p.p.m. level for 1-g samples is less than 3 %.