1Japan Special Steel Co., Ltd., Research Laboratory, Tokyo
This experiment was carried out on the spectrophotometric method with stilbazo, in order to establish a simple and accurate method for the determination of the tin content in iron and steel.
The tin (IV) reacts with stilbazo in an acetic acid-sodium acetate medium to give a complex which shows an absorption maximum at the wave length of 505 milli microns. This complex is stable for 30 min. At the wave length of 505 milli microns, the relation between the amounts of tin and the absorption follows Beer's law in the range from 0 to 100 γ/100 mL of tin. The absorption of this complex is constant at pH 5.0 ∼ 6.0, when absorption was measured against a blank solution. In this method, there is no significant effect even in case 2 mg each of iron, chromium and beryllium, 5 mg each of manganese, nickel and cobalt, 0.2 mg each of copper and bismuth, 1 mg each of arsenic and lead are contained in the separated sample solution. Alminium, antimony, molybdenum, niobium, (tantalum, titanium tungsten, vanadium and zirconium interfere.
The tin was separated from various elements by co-precipitation of the tin with beryllium hydroxide in an ammonical solution containing EDTA, and precipitation as the tin-thionalide complex in a sulfric acid solution containing tartaric acid.
As a result of the experiment, the author succeeded to establish a method in which less than 0.1% of tin in iron and steel can be measured easily and accurately. The tin content in actual samples was measured by this method with satisfactory results.
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