分光光度法同时测定微量铁和钴

SIMULTANEOUS DETERMINATION OF IRON(Ⅱ) AND COBALT(Ⅱ) BY SPECTROPHOTOMETRY

在碱性介质中,铁(Ⅱ)和钴(Ⅱ)可与硫代巴比妥酸-NO2-体系反应分别形成一种稳定的兰色和黄色配合物,铁(Ⅱ)配合物在656nm和386nm具有吸收峰,钴(Ⅱ)配合物只有一个吸收峰位于423nm,体系的吸光度A6Fe56、A4F2e3、AC42o3与铁、钴含量在一定的范围内呈良好的线性关系,且铁(Ⅱ)、钴(Ⅱ)配合物在423nm波长处的吸光度具有良好的加和性,建立了一种同时测定微量铁和钴的新的分光光度法。方法的线性范围分别为铁0～50μg/(25mL)、钴0～25μg/(25mL)。将该法应用于水样中微量铁和钴的同时测定,其结果分别与原子吸收光谱法和紫尿酸光度法相吻合,加标回收率分别为98%～102%和94%～106%,相对标准偏差(RSD)分别为1.0%～1.8%和3.1%～4.7%(n=5)。

In a base medium, iron（ Ⅱ） and cobalt（ Ⅱ） reacted with thibarbiuric acid -NO2^- to form blue and yellow complex, respectively. The absorption peak of complex were at 656 nm, 386 nm for iron（ Ⅱ） and 423 nm for cobalt（ Ⅱ）. The absorbance at 423 nm of the two complex had additive property. A new method for simultaneous determination of trace iron and cobalt by the spec- trophotometry with thibarbiuric acid -NO2^- was established. Beer＇s law was obeyed in the range of 0 -50 μg/（25 mL） for iron and 0 -25 μg/（25 mL） for cobalt. When the method was applied to determine iron and cobalt in water, the results were in good agreement with those obtained by AAS and nitroso - R - salt spectrophotometry. The recoveries were 98% - 102% for iron （ Ⅱ） and 94% - 106% for cobalt（ Ⅱ）. The relative standard deviations of iron（ Ⅱ） and cobalt （ Ⅱ） were 1.0% -1.8% and 3.1% -4.7% （n = 5）, respectively.