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目的 :对目前基层碘盐监测主要采用的碘酸钾食盐定量测定方法直接滴定法进行探讨。方法 :通过对硫代硫酸钠标准溶液配制、终点判定、方法名称的系统研究 ,进而找出原方法中不够严谨的部分。结果 :找到并指出了问题的关键 ,为方法的改进提供了理论依据。结论 :硫代硫酸钠标准溶液配制应标定 ;终点判定部分应把“滴定至终点后 ,经过 5min以上 ,经空气氧化I-可使溶液复现兰色 ,但这并不影响检测结果。”加上 ,使表述更严谨 ;方法名称应改为“置换滴定法”。
OBJECTIVE: To investigate the direct titration method for the quantitative determination of potassium iodate in the primary iodized salt monitoring. Methods: A systematic study on the preparation of sodium thiosulfate standard solution, determination of the end point and the method name was conducted, and then the less rigorous part of the original method was identified. Results: The key to finding and pointing out the problem provides the theoretical basis for the improvement of the method. Conclusion: The preparation of sodium thiosulfate standard solution should be calibrated. The determination of the end point should be titrated to the end, after more than 5min, air oxidation I- can make the solution blue, but this does not affect the test results. , So that the statement more rigorous; method name should be replaced by “replacement titration.”