水相中铋(Ⅲ)-碘化钾-乙基紫缔合反应的研究—分光光度法测定微量铋

Spectrophotometric Determination of Bi(Ⅲ)in Ores with Ethyl Violet

在pH 3.0~4.5范围,水相中缔合物(EV)_(2)[BiI_(6)](λ_(max)=540nm)同试剂(λ_(max)=650nm)有较大的对比度。在完成缔合后的体系中加入适量酸,过量乙基紫阳离子质子化使对比度、灵敏度增高。用于微量铋的测定,0~24μg/25ml范围符合比尔定律,表观摩尔吸光系数为2.05×10^(5)。用于样品分析结果满意。

A highly sensitive method for the spectrophotometric determination of bismuth(Ⅲ)with potassium iodide and ethyl violet in the presence of Arabic gum in 0.018-0.028 N HC1 has been developed.Metachromatism was observed when Arabic gum was added to the dye solution.The ion-associate has the composition of(EV)_(2)·[BiI_(6)]and its apparent molar absorptivity is 2.05×10^(5) l.mol^(-1).cm^(-1) at 540 nm Beer’s law was obeyed for 0-24μg/25 ml of bismuth.The ion-associate is stable for at least 1.5 hour at 10-25℃.This method has been applied to the determination of microamounts of bismuth in ores.