铁的单点络合滴定法研究

Study on Single-point Complexometric Titration of Iron

本文研究了Fe^(3-)的单点络合滴定法,导出了定量关系式,比较了以铂电极为指示电极和以 PVC膜四氯络铁(Ⅲ)阴离子电极为指示电极时电位测量的稳定性及所得的分析结果.在Fe^(3-)浓度为1.00×10^(-3)mol/L时.18次实验的平均值为1.00×10^(-3)mol/L,相对偏差为0.2%;Fe^(3-)的浓度为1.00×10^(-4)mol/L时,15次测定的平均值为及1.02×10^(-4)mol/L,相对偏差小于1.7%;Fe^(3+)在5.0×10^(-5)mol/以上时,相对偏差小于0.1%;其浓度小于10^(-3)mol/L而大于5×10^(-4)mol/L时,相对偏差小于0.5%,且精密度好,该法分析 Fe^(3+)简单,快速,精密度高.准确度好,可实现无汞,无K_2Cr_2O_7,定铁,并可自动化.

The method for the complexometric titration of iron using EDTA as complexing a-gent was studied, and the quantitative equation is given. Pt electrode and PVC-based membrane tetrachloroferrate ( Ⅲ ) ion-selective electrode were used as indicating electrode. The stabilization of the electrode potential of the two electrodes as well as the results of the analysis were compared. At [Fe3+]=1. 0×10×3 mol/L, the average value of 18 determination is 1. 00×10-3 mol/L, relative error is 0. 2%. At Fe3+ concentration 1. 00×10-4 mol/L, the average value of 15 determinations is 1. 02× 10-4 mol/L, relative error is 1. 7%. The analytical results are very satisfactory. The simple and fast method can be automated, and avoid the use of mercuric chloride and potassium dichromate.