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在水溶液中用分光光度法研究了偶氮胂Ⅲ与稀土元素镧、钆的反应。在 pH=2.99和 pH=4.79时测得偶氮胂皿及其与镧、钆配合物的吸收曲线。得到介质酸度及配合剂用量对配合物吸光度的影响。仅在 pH=2.7～3.0范围内吸光度变化不大。配合剂用量增加吸光度增大。并用摩尔比法、等摩尔连续变化法及平衡移动法测得镧、钆与偶氮胂Ⅲ的配合物的组成比为1:1,而且还存在1:2的配合物。同时测定了它们的稳定常数。
The reaction of arsenazo Ⅲ with rare earth lanthanum and gadolinium was studied by spectrophotometry in aqueous solution. The absorption spectra of arsenazo and its complexes with lanthanum and gadolinium were measured at pH = 2.99 and pH = 4.79. The medium acidity and the amount of complexing agent on the absorbance of the complex were obtained. Only in the range of pH = 2.7 ~ 3.0 little change in absorbance. Increasing the amount of dosage increases absorbance. The composition ratio of lanthanum, gadolinium and arsenazo Ⅲ complexes was 1: 1 by molar ratio method, equimolar continuous variation method and equilibrium shift method, and a 1: 2 complex existed. Their stability constants were also determined.