空气中汞的滴定分析方法研究

Study of Titrimetric Determination of Mercury in Air

[目的]建立空气中汞的滴定分析方法。[方法]以碘化钾作滴定剂，I^-与Hg^2＋形成稳定的[HgI4]^2-，当滴定到终点时，微过量的I^-迅速催化三氧化二砷和硫酸铈的氧化还原反应而放出热量。根据能斯特方程，利用离子选择电极对温度敏感的特点，当溶液温度突然升高时电位迅速下降，从而指示了滴定反应的终点。[结果]以0．5～5．0μgHg^2＋作标准曲线，相关系数为0．998；精密度实验结果，其变异系数在3．57％～6．89％之间；回收率实验，结果在93．4％～103．5％之间。[结论]该方法原理新颖，操作简单，重现性好，准确度高。

[Objective]To establish titrimetric determination of mercury in air. [Methods] Take potassium iodide as titrant ,I^- and Hg^2＋ form a stable [HgI4 ]^2- ,when titration goes to the end,redox reaction of arsenic trioxide and cerous sulfate was rapidly catalyzed by a bit excessive I^- and heat was released. Based on the Nernst equation and sensitive characteristic to the temperature of specific ion electrode , when the temperature suddenly increased , the electric potential declined rapidly,which indicated the end of titration reaction. [Results]When the standard curve was from 0.5 to 5.0 μg Hg%2＋ ,correlation coefficient was 0. 998, the coefficient of variation was from 3.57 % to 6.89 % after precision experiment. The recovery rate was from 93.4% to 103.5%. [Conclusion]The principle of the method is new and original,easy to operate with good reappearance and high,accuracy.