Studies on Rapid Analysis of Iron and Steel by Photometry (IV). Rapid Photometric Determination of Small amounts of Chromium and Nickel in Iron and Steel

Abstract

The author studied the photometric method for the determination of small amounts of chromium and nickel in iron and steel and found the following most suitable: Cr; Dissolve a sample in a mixture of HNO₃, H₂SO₄ and H₃PO₄, add KMnO₄, reduce the excess of KMnO₄ with urea and NaNO₂, add diphenylcarbazide, add HF to prevent the interference of Fe⁺⁺⁺ and measure the extinction. This method requires only 12 to 13 minutes and is applicable to iron and steel containing 0.005 to 0.78% of Cr. Ni; Dissolve a sample in HNO₃ and HClO₄, evaporate to fume, cool, add water to dissolve salts, dilute to 250 mL, take 25 mL of the supernatant liquid into a measuring flask of 100 mL, add citric acid and NH₄OH, mix well, cool, then add I₂ and dimethylglyoxime NaOH solution, dilute to the mark and measure the extinction. The time for analysis is only 10 to 12 minutes and 0.001 to 0.7% of Ni can be determined by this method.