An improved nephelometric method for the determination of small amounts of thiosulfate in aqueous samples

The procedure is based on decomposition of thiosulfate, with formation of sulfur, in the presence of 0.5 mol l^?1 nitric acid. Thiosulfate is determined in the range 15–100 mg l^?1, with a relative standard deviation of 5.4% and a mean relative error of 3.2%. These data are of the same order of magnitude as those obtained for the earlier silver/1,10-phenanthroline method. The present method has the advantage of being almost completely free from interferences; the only interference observed (sulfide) is easily eliminated.