鉄鋼中のマンガン迅速定量法として過硫酸アンモニウム酸化,チオ硫酸ナトリウム滴定法の検討

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Rapid determination of manganese in iron and steel by oxidation with ammonium persulfate and titration with sodium thiosulfate is investigated. The reaction of permanganic acid and sodium thiosulf ate is proceeded in a ratio close to 8M : 5M. A standard solution close to 1/250 M Na2S2O3 (1 g Na2S2O3·5H2O/l) is standardized in every 10 days against the standard ferro-manganese solution or standard steel; 0.2 g sample containing 0.32.0 mg Mn is treated according to the method of Japanese Science Development Association or JIS method, cooled below 35°C and the solution is titrated with the standard solution with good reproducibility. The end point of those with the use of nitric acid was clear in the same way as those with the use of sodium arsenite method, especially those with the use of sulfuric acid-nitric acid mixture, and those titrated at night with the use of fluorescent light gave better result. The Mn equivalency per 1 cc standard solution is not variable by the change in amount of Mn content and the titration is not influenced by the change in amount of Mn content and the titration is not influenced by the presence of 50% Ni and 0.5% Cu, also the presence of <0.25% Cr or <3% Co gave no disturbance. The standard solution of this method is nontoxic and the method of preparation is simple in comparison with the other standard solutions.
社団法人日本分析化学会の論文