次亜塩素酸塩法による臭素イオン,ヨウ素イオンの容量分析

概要

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Fundamental conditions for the volumetric determination of bromide or iodide ion by iodometry have been investigated. Each ion is oxidized to bromate or iodate with hypochlorite. The suitable pHs for the oxidation are 19 in the case of iodide and 78.3 in the case of. bromide. Bromide is not oxidized to bromate at pH<2, whereby only iodide is oxidized to iodate. The excess of hypochlorite is completely decomposed at pH<7 with sodium formate, but bromate is also decomposed at pH<3 and iodate at pH<2.6. Consequently the excess of hypochlorite must be decomposed at pH37. One of the reasons for an appearance of blank values is the presence of a trace amount of hypochlorite which is not decomposed with formate. The amounts of reagents and their adding order are studied. The addition of ammonium molybdate as a catalyzer is not necessary. The effects of diverse salts are examined, whereby sodium chloride as much as 3 g does not interfere. The proposed method does not need a buffer solution and may by applicable to the determination of small amount of bromide or iodide in the presence of one another.
社団法人日本分析化学会の論文