利用在碱性介质中,铁(Ⅱ)和钴(Ⅱ)可与硫代紫尿酸反应分别形成稳定的蓝色和黄色配阴离子,铁(Ⅱ)配阴离子在658 nm和395 nm具有吸收峰,钴(Ⅱ)配阴离子只有一个吸收峰位于424 nm,体系的吸光度AFe,658、ACo,424与铁、钴含量在一定的范围内呈线性关系,且铁(Ⅱ)、钴(Ⅱ)配阴离子在424 nm波长处的吸光度具有良好的加和性,在658 nm测定铁,在424 nm测定钴的质量浓度分别在50.0 μg/25 mL和25.0 μg/25 mL以内符合比耳定律,该方法应用于水样中微量铁和钴的同时测定,其结果与原子吸收光谱法相吻合,加标回收率分别为98%~104%和97%~103%,相对标准偏差(n=5)分别在1.8%~3.4%和2.2%~3.7%.

In a borate buffer medium of pH 9.0,stable colored coordination complex was formed between the color reagent,thiovioluric acid (TVA) and iron(Ⅱ) or cobalt(Ⅱ). The coordination complex of TVA and Fe(Ⅱ) showed 2 absorption peaks at wavelengths of 658 nm and 395 nm in its absorption spectrum,while that of TVA and Co(Ⅱ) showed only one absorption peak at 424 nm. It was proposed that determination of iron was performed by measuring the absorbance values at 658 nm,and determination of cobalt at 424 nm where significant absorption of the Fe(Ⅱ)-TVA complex was also happened. Based on the additivity of absorbances of the complexes,a formula for calculation of content of cobalt was given. Linear relationships between values of absorbance and mass concentration of iron and cobalt were found in the ranges within 50.0 μg and 25.0 μg per 25 mL respectively. The proposed method was used for determination of Fe and Co in water samples giving results in consistency with the results found by AAS. Values of recovery found by standard addition method were ranged from 98%-104% and 97%-103% with values of RSD′s (n=5) ranged from 1.8% to 3.4% and 2.2% to 3.7% respectively.