基于全自动电位滴定测定食盐中碘含量的方法研究

Study on the method of determining iodine content in salt based on automatic potentiometric titration

目的利用全自动电位滴定仪建立一种快速简便测定碘酸钾盐中碘含量的方法,同时探究国标《制盐工业通用试验方法碘的测定》(GB/T 13025.7—2012)中的部分条件应用在电位滴定法中的可行性。方法应用全自动电位滴定法测定食盐中碘含量,开展条件优化、精密度、准确度等实验。结果利用本方法测定两种质控盐样与标准值的相对误差分别为0.08%~2.07%和-1.18%~3.08%,平行测定6次样品的相对标准偏差(RSD)分别为0.65%和1.37%;在两种不同浓度的实际食盐样品中的三个加标回收率结果分别为92.6%~98.0%、97.7%~103.8%、94.4%~94.7%。结论本方法可以利用食盐中碘酸钾与硫代硫酸钠反应过程中产生的电位变化对盐中碘含量进行准确快速的测定,具有良好的精密度、准确度,具有一定的基层盐碘检测应用可行性。

Objective To establish a rapid and simple method for the determination of iodine in potassium iodate by automatic potentiometric titrator,and to explore the feasibility of the application of some conditions in the national standard"General Test Method in Salt Industry Determination of Iodine"(GB/T 13025.7—2012).Methods The iodine content in salt was determined by automatic potentiometric titration,and the experiments of condition optimization,precision and accuracy were carried out.Results The relative errors were 0.08%-2.07%and-1.18%-3.08%for determination of two kinds of quality control salt samples,and the relative standard deviations(RSD)were 0.65%and 1.37%,respectively.The recoveries were 92.6%-98.0%,97.7%-103.8%and 94.4%-94.7%in two different concentrations of actual salt samples.Conclusion This method can be used to determine the iodine content in salt accurately and quickly by the potential change generated during the reaction of potassium iodate and sodium thiosulfate in salt.It has good precision and accuracy,and has certain feasibility for the application of iodine detection in grass-roots unit.