水蒸気蒸留法によるフェロアロイおよび金属中の窒素の定量

概要

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A rapid method for the determination of nitrogen in ferro-alloys and metals has been established. The method is as follows. In cases of ferrosilicon, ferroniobium, silicon metal and tantalum metal, 2 g of sample is decomposed with 10 ml of water, 5 ml of hydrobromic acid, 15 ml of hydrofluoric acid, 15 ml of hydrogen peroxide (10%) and 3 g of oxalic acid [on calcium-silicon, 40 ml of phcsphoric acid (1+4), silicon-titanium, silicon-manganese and silicon-chromium by using 20 ml of sulfuric acid (1+1)] and then hydrofluoric acid is masked by 5 g of boric acid. After masking, nitrogen is separated with steam distillation method, and more than 0.03% of nitrogen is titrated by using standard sulfamic acid solution. A small amount of nitrogen is usually determined by photometry with Nesslers reagent. In cases of ferro-alloys and metals, the sample is decomposed with a mixture of 50 ml of sulfuric acid (1+4) and 20 ml of hydrochloric acid, or that of 10 ml of sulfuric acid, 10 ml of phosphoric acid and 10 g of potassium sulfate.
社団法人日本分析化学会の論文