表面活性剂增敏邻菲啰啉光度法测铁的研究

Spectrophotometric study on surfactant sensitizing the chromogenic reaction of Fe(Ⅱ)with o-phenanthroline

研究了阳离子表面活性剂溴化十六烷基三甲胺 (CTMAB)增敏邻菲啉测Fe(Ⅱ )的反应条件 ,建立了测定铁的新方法。在pH 3 .0～ 4. 0的条件下 ,CTMAB的存在增加了邻菲啉显色反应的灵敏度 ,其最大吸收波长为 5 10nm ,表观摩尔吸光系数为 1 .0× 10 .5L·mol-1·cm-1,铁含量在 0 . 2～ 10 μg/mL范围内服从比尔定律 ,可用于水样中铁的测定 ,回收率在95 . 4 %～ 97. 7%之间。

The chromogenic reaction of Fe(Ⅱ) with o-phenan throline was studied in the presence of reductant such as ascorbic acid and positive ion surfactant CTMAB,Fe(Ⅱ) was capable of reacting with o-phenanthroline to form a stable,positively charged,orange complex in the pH range 3.0 to 4.0.The complex had a 3∶1molar ratio for o-phenanthroline and Fe(Ⅱ).In the presence of positive ion surfactant CTMAB,the sensitivity of chromogenic reaction was largely improved.At the maximum absorption wavelength of 510nm,the apparent molar absorptivity was 1.0×105L·mol -1·cm -1.Beer′s law was obeyed in the range of 0.2 to 10μg/mL Fe(Ⅱ).Satisfactory result was achieved in applying the method to determination of trace iron in water.