新试剂5-(5-碘-2-吡啶偶氮)-2,4-二氨基甲苯高选择性分光光度法测定微量Pd(Ⅱ)

Highly Selective Spectrophotometric Determination of Trace Palladium(Ⅱ) Using a New Reagent 5-(5-Iodine-2-pyridylazo)-2,4-diaminotoluene

研究了新试剂5-(5-碘-2-吡啶偶氮)-2,4-二氨基甲苯(5-I-PADAT)与Pd(Ⅱ)的显色反应。实验结果表明,在0.6～1.8mol/L高氯酸介质中,于室温下放置10min,Pd(Ⅱ)与5-I-PADAT可形成1∶1蓝紫色络合物,其最大吸收波长位于583nm,表观摩尔吸光系数ε为7.2×104L·mol-1·cm-1,Pd(Ⅱ)的浓度在0～1.0μg·mL-1符合比耳定律。由于反应直接在强酸性介质中进行,而在此酸度下,其它金属离子几乎不能反应,因此具有极高的选择性。所拟方法操作简单、快速,可应用于合金、矿样和分子筛中微量钯的测定。

A new reagent, 5- （5-iodine-2-pyridylazo）-2,4-diaminotoluene （5-I-PADAT）, was recommended for the determination of palladium. In strong acidic media,palladium（ II ） could react with 5-I-PADAT at room temperature to form a 1 ＂ 1 stable blue-purple complex with the maximum absorption wavelength located at 583 nm. The apparent molar absorptivity was 7. 2 X 104L. tool-1. cm-1 in 1. 2 tool. L 1 perchloric acid. Beer＇s law was obeyed in the range of 0 - 1.0 μg. mL 1 for palladium. The common metal ions did not interfere with the determination of palladium. The method was simple and rapid, with very high selecitivity and good sensitivity. It was used in the determination of palladium in molecular sieve,alloy and ore with satisfactory results.