国家标准《制盐工业通用试验方法碘离子的测定》仲裁法探讨与改进

Method Improvement of Arbitration Law in National Standards "General Test Method in Salt Industry-Determination of Iodide Ion"

目的探讨氧化还原法测定川盐碘离子含量方法存在的问题,提出改进措施。方法通过采用向直接滴定法体系中加入草酸,分析草酸对硫代硫酸钠还原碘酸根的干扰,对氧化还原法次氯酸钠的用量进行试验。结果在0.06%草酸溶液中,草酸不干扰碘酸钾和碘化钾的反应及硫代硫酸钠还原碘酸根的反应。结论仲裁法中改进次氯酸钠浓度和用量,保证体系中草酸适度过量,能准确测定川盐中碘离子含量。

Objective To investigate the possible flaws in oxidation reduction method in the determination of salt iodine ion content and put forward the improvement measures. Methods With oxalic acid directly dripped into titration system, the interference of oxalic acid on sodium thiosulfate reduction of iodate was observed, and afterwards, the content of the sodium hypochlorite was tested. Results In the 0. 06% oxalic acid solution, the oxalic acid did not interfere with the reactions between potassium iodate and potassium iodide, as well as the sodium thiosulfate reduction reaction. Conclusion In the arbitration law, by appropriately adjusting the concentration and dosage of sodium hypochlorite, the iodine ion content in salt can be accurate determined.