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研究〔I2 Br〕-络阴离子与乙基紫、结晶紫、维多利亚蓝 4R等碱性三芳基甲烷染料在聚乙烯醇存在下的离子缔合反应的条件、分光光度特征和分析化学性质。结果表明 ,在稀磷酸介质中 ,当形成上述离子缔合络合物时 ,溶液均发生明显的颜色变化。不同染料体系的摩尔吸光系数在 2 .6× 10 4 ～ 6 .2×10 4 L·mol-1·cm-1之间 ,以乙基紫体系灵敏度最高。碘离子浓度在 0～ 1.6mg/L(乙基紫体系 )、0～ 1 4mg/L(结晶紫体系 )和 0～ 0 .8mg/L(维多利亚蓝体系 )符合比耳定律 ,可用于水相直接显色测定碘离子。方法也有良好的选择性 ,较大量的其他卤离子、一些无机酸根以及一定量的常见金属离子不干扰。用于海带、紫菜和黄豆中碘离子的测定 ,结果较为满意。
The conditions, spectrophotometric characteristics and analytical chemistry of [I2Br] - complex anion and ion exchange reaction of basic triarylmethane dyes such as ethyl violet, crystal violet and victoria blue 4R in the presence of polyvinyl alcohol were studied. The results show that in the dilute phosphoric acid medium, when the above-mentioned ionic association complex is formed, the solution undergoes obvious color change. The molar absorptivities of different dye systems ranged from 2.6 × 10 4 to 6.2 × 10 4 L · mol -1 · cm -1, and the highest sensitivity was obtained with ethyl violet system. The iodine ion concentration is in the range of 0-1.6 mg / L (ethyl violet system), 0-1 4 mg / L (crystal violet system) and 0-0.8 mg / L (Victoria Blue system) Direct colorimetric determination of iodide. The method is also well-selective, with larger amounts of other halide ions, some inorganic acid radicals, and a certain amount of common metal ions. For kelp, seaweed and soybeans in the determination of iodine, the results are more satisfactory.