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研究了新合成试剂5-(5-碘-2-吡啶偶氮)-2,4-二氨基甲苯(5-I-PADAT)与钌(Ⅱ)的显色反应。实验表明,在30%乙醇存在下于pH 4.0~6.2 HAc-NaAc缓冲介质中,钌(Ⅱ)与5-I-PADAT形成稳定的配合物,其最大吸收波长位于529 nm。该配合物在无机酸(HCl,H2SO4,HClO4,H3PO4)作用下,可转变为另一种具有较高吸收特性的配合物,其最大吸收波长位于509 nm,适宜的酸浓度范围分别为0.15~0.60 mol/L HCl,0.15~0.48 mol/L H2SO4,0.15~0.48 mol/LHClO4和0.15~0.90 mol/L H3PO4。表观摩尔吸光系数5ε09=5.72×104L.mol-1.cm-1,钌含量在0~0.5μg/mL内符合比尔定律。40倍的银、10倍的锇、6倍的金和4倍的Pt、Rh、Ir等贵金属离子不干扰钌的测定,钯的干扰可利用其与钌(Ⅱ)显色温度和酸度的差异性消除。方法可用于催化剂中微量钌的测定。
The color reaction of 5- (5-iodo-2-pyridylazo) -2,4-diaminotoluene (5-I-PADAT) with ruthenium (Ⅱ) was studied. Experiments show that ruthenium (Ⅱ) forms a stable complex with 5-I-PADAT in pH 4.0 ~ 6.2 HAc-NaAc buffer medium in the presence of 30% ethanol at a maximum absorption wavelength of 529 nm. Under the action of inorganic acids (HCl, H2SO4, HClO4, H3PO4), the complex can be transformed into another complex with higher absorption characteristic, the maximum absorption wavelength is at 509 nm and the suitable acid concentration range is 0.15 ~ 0.60 mol / L HCl, 0.15-0.48 mol / L H2SO4, 0.15-0.48 mol / LHClO4 and 0.15-0.90 mol / L H3PO4. Apparent molar absorption coefficient 5ε09 = 5.72 × 104L.mol-1.cm-1, ruthenium content in 0 ~ 0.5μg / mL within Beer’s Law. 40 times of silver, 10 times of osmium, 6 times of gold and 4 times of Pt, Rh, Ir and other precious metal ions do not interfere with the determination of ruthenium. The interference of palladium can be used for its difference from the color temperature and acidity of ruthenium (II) Elimination. The method can be used for the determination of trace ruthenium in catalysts.