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研究了铁(Ⅱ)与新显色剂2(5溴2噻唑偶氮)-5二乙氨基苯酚(5-BrTADAP)的显色反应.它们在pH 7-10的溶液中形成难溶于水的1∶2棕色络合物,其表观稳定常数为3.94×10~(10)(20℃).用氯仿萃取的Fe(Ⅱ)5 Br TADAP络合物在572nm和772nm有两个吸收峰,其表观摩尔吸光系数分别为3.94×10~4L·mol~(-1)·cm~(-1)和3.10×10~4L·mol~(-1)·cm~(-1),灵敏度是1.10二氮杂菲法的34倍.其他金属离子与该试剂形成的络合物在近红外区的772mm附近均无吸收,因此在772mm处分光光度测定痕量铁有很高的选择性.在10毫升体积中,铁量在0-25微克范围内遵从比耳定律.本法简便、快速、准确可靠,将其用于黄铜和高硅铝合金中铁的测定,取得了令人满意的结果.
The color reaction of iron (II) with a new chromogenic reagent 2 (5-bromothiazolylazo) -5-diethylaminophenol (5-BrTADAP) was studied in the presence of a solution of The apparent stability constant was 3.94 × 10 ~ (10) (20 ℃). The Fe (Ⅱ) 5 Br TADAP complex extracted with chloroform had two absorption peaks at 572 nm and 772 nm The apparent molar absorptivities were 3.94 × 10 -4 L · mol -1 · cm -1 and 3.10 × 10 -4 L · mol -1 · cm -1 respectively. The sensitivity Which is 34 times higher than that of phenanthroline 1.10 The complex formed by other metal ions with this reagent has no absorption near 772mm in the near infrared region and therefore high spectrophotometric determination of trace iron at 772mm is highly selective. Beer’s law is obeyed in the range of 0-25 micrograms of iron in a volume of 10 ml.The method is simple, rapid, accurate and reliable and is applied to the determination of iron in brass and high-silicon aluminum alloy, and has achieved satisfactory result.