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目的:建立用显色剂2-(5-溴-2-吡啶偶氮)-5-二乙氨基酚(简称为5-Br-PADAP)测定水中微量铁的方法。方法:在pH=6.0的醋酸-醋酸钠缓冲体系中,采用阴离子表面活性剂十二烷基硫酸钠(SDS)增溶增敏,铁(II)与显色剂形成稳定的紫红色化合物,用分光光度法测定铁。结果:铁(II)与显色剂形成的配合物组成为Fe(II):R=1:2,络合物具有两个吸收峰,分别位于λ1=556 nm与λ2=745 nm。选择745 nm进行测定,其摩尔吸光系数为ε745=3.4×104(L/mol.cm)。铁含量在0~30μg/25 ml范围内服从比尔定律。方法的加标回收率为95.3%~102.3%,相对标准差为2.9%。结论:此法用于水样中微量铁的测定,结果准确可靠。
Objective: To establish a method for the determination of trace iron in water with 2- (5-bromo-2-pyridylazo) -5-diethylaminophenol (abbreviated as 5-Br-PADAP) Methods: An anionic surfactant sodium dodecyl sulfate (SDS) was used to solubilize and sensitize in pH = 6.0 acetic acid-sodium acetate buffer system. The iron (II) and the chromogenic reagent formed a stable purple compound with Spectrophotometric determination of iron. Results: The complex formed by iron (II) and chromogenic reagent is Fe (II): R = 1: 2. The complex has two absorption peaks at λ1 = 556 nm and λ2 = 745 nm, respectively. Choose 745 nm for determination, the molar absorption coefficient of ε745 = 3.4 × 104 (L / mol.cm). Beer’s law is obeyed in the range of 0 ~ 30μg / 25ml. The recovery of the method was 95.3% ~ 102.3% with the relative standard deviation of 2.9%. Conclusion: This method is applied to the determination of trace iron in water samples with accurate and reliable results.