抑制-褪色光度法测定痕量铁(Ⅲ)

Determination of Trace Iron by Inhibition Discoloring Spectrophometry

基于ＮａＯＨ介质中，溴化十六烷基三甲铵（ＣＴＭＡＢ）作为增稳剂时， Ｐｅ（Ⅲ）能抑制Ｈ２０２氧化桑色素的褪色反应，提出了一种高灵敏度测定痕量铁的新方法。该方法的表观摩尔吸光系数为３．１×１０７ Ｌ·ｍｏ１－１·ｃｍ－１，线性范围为０．０４～０．２０ μｇ Ｆｅ（Ⅲ）／Ｌ作曲线的回归方程为ΔＡ＝－４．０Ｘ×１０－４＋０．５５５×ＣＦｅ（Ⅲ）（μｇ／Ｌ），相关系数 ｒ＝０． ９９９８，检出限 ４． ０× １０－９ｇ／Ｌ．本方法用于水样中 Ｆｅ（Ⅲ）的测定，结果满意。

A new highly sensitive spectrophotometric method for the determination of trace iron was proposed on the inhibition effect of Fe(Ⅲ) on discoloration reaction between morin and H2O2 in NaOH medium and in the presense of C etyltrimethylammonium bromide as a stabilzer The apparentε 420=3.1×107-L·mol-1·cm-1.the Beer's law, is obeyed in the range of 0.04-0.20μgFe(Ⅲ)/L with a finear regression equationΔ A=-4.0× 10-4+O.555 × CFe（Ⅲ）（μg/L),r=0.9988. The detection limit 4.0 ×10-9g/L. The method has been used for the determination of Fe(Ⅲ) in water samples with the satisfatory results.