新显色剂6-Br-BTACPACA的合成及双波长褪色分光光度法测定铁(Ⅲ)的研究

Synthesis of 6-Br-BTACPACA and Study on its Colour Reaction with Iron(Ⅲ) by Dualweavelength Decolouration Spectrophotometry

合成一种新的杂环不对称双偶氮变色酸显色试剂2 (6 溴 2 苯并噻唑偶氮) 7 (4 羧基苯偶氮) 1,8 二羟基萘 3,6 二磺酸.采用双波长褪色分光光度法研究在pH=8.4的NH3·H2O NH4Cl缓冲介质中显色试剂与铁(Ⅲ)的显色反应特性.结果表明:在CTMAB存在下试剂与铁(Ⅲ)形成3∶1的配合物,显色反应5min完全并至少可稳定2h,以配合物为参比试剂空白的最大吸收波长为450nm和620nm,表观摩尔吸光系数为4.87×104L·mol-1·cm-1,铁(Ⅲ)的质量摩尔浓度在0～10μg/25ml范围符合比耳定律.用拟定的方法测定石灰石、高炉渣中铁的含量得到满意的结果.

\ The synthesis of 2(6Bromo2benzothiazylazo)7\%p\%carboxylazo1,8dihydroxynaphthalene3,6disulfonic acid (6BrBTACPACA) and its colour reaction with Fe(Ⅲ) were studied spectrophotometrically.In the presence of CTMAB iron reacts with 6BrBTACPACA to form a stable complex in pH 8.40 NH\-3·H\-2ONH\-4Cl buffer solution.The ratio of \%n\%\-\{Fe\}:\%n\%\-\{6BrBTACPACA\} in the complex is found to be \{1∶3\}.The chromogenic reaction completes with 5 min and is stable for at least 2 h. Beer's law is obeyed in cocentration range of 0～10 μg/25 ml for Fe(Ⅲ). The method is moderate sensitive and selective and has been used for rapid determination of Fe(Ⅲ) in standard slag and limestone with satisfactory results.