紫尿酸双波长叠加光度法测定水中微量铁

Determination of Iron in Water by DW-Spectrophotometry with Absorbance Addition

在碱性介质中，铁（Ⅱ）与紫尿酸发生显色反应形成一种蓝色配阴离子，该配阴离子具有两个吸收峰，分别位于630nm和350nm，吸光度A630，A350之和△A与铁（Ⅱ）的含量在0-2μg／mL范围内线性关系良好，据此建立了测定微量铁的紫尿酸双波长叠加光度法，该法用于水中微量铁的测定，测定结果与火焰原子吸收法（FAAS）相吻合，加标回收率为98％-102％，测定结果的相对标准偏差为1．2％-2．9％（n=5）。

A new dual-wavelength spectrophotometry for the determination of iron by measurement with absorbance addition was proposed. In a base medium, iron（ Ⅱ ） reacted with violuric acid to form a blue complex with 2 absorption peaks at wavelengths of 630 nm and 350 nm. Applying the measurement mode of ＂absorbance addition at 2 wavelengths＂, i.e., by taking the sum of values of the absorbances at 630 nm and 350 nm （ △A= A630＋ A350 ）, a linear relationship between the sum of absorbances and the mass concentration of iron was obtained in the range of 0 - 2 μ g/mL. The determination result of trace iron in water was in good agreement with that obtained by FAAS. The recoveries were 98% - 102%, and the RSD were 1.2% - 2.9%（n=5）.