乳化剂CTMAB-5-Br-PADAP分光光度法测定微量铁

Spectrophotometric Determination of Trace Iron (Ⅱ) with-5-Br-PADAP in the Presence of CTMAB

研究了在阳离子表面活性剂 CTMAB存在下 ,Fe( )与 2 - (5-溴 - 2 -吡啶偶氮 ) - 5-二乙氨基苯酚 (5-Br- PADAP)的显色反应。试验表明 ,在 p H=3.6— 6 .4范围内 ,Fe( )与 5- Br- PADAP形成稳定的红色络合物 ,最大吸收峰位于 559nm和 74 9nm。在 74 9nm处 ,络合物的表观摩尔吸光系数为 3.1× 10 4 L·mol-1· cm-1,组成比为 Fe( )∶ 5- Br- PADAP=1∶ 3,铁量在 0— 50 μg/ 2 5m L范围内符合比耳定律。方法选择性较高 ,用于水样中微量铁的测定 。

Color reaction of iron(Ⅱ) with 2 (5 bromo 2 pyridylazo) 5 diethylaminophenol(5 Br PADAP) has been studied in the presence of cationic surfactant CTMAB.Iron(Ⅱ) reacts with 5 Br PADAP at pH 3.6—6.4 to form a stable 1∶3 complex in aqueous solution.The apparent molar absorptivity of the complex is 3.1×10 4L·mol -1 ·cm -1 (at 749nm).Beer's law is obeyed in the range of 0? ?0μg/25mL for iron(at 749nm).The proposed method has been applied to the determination of trace iron in water with satisfactory results.