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目的:建立了双指示剂催化动力学光度法测定痕量铜的新方法。方法:在酸性介质中,铜离子催化甲基橙和亚甲基蓝双指示剂的氧化褪色反应,通过催化体系和非催化体系吸光度变化与铜离子浓度之间的关系,建立了测定痕量铜的方法。结果:铜(Ⅱ)在0.005 0～0.160 mg.L-1,与催化反应速度成线性关系可以进行含量的测定。结论:该方法方便、准确、重复性好,可以作为测定了黄芪苦参中微量的铜(Ⅱ)元素的方法。
Objective: To establish a new method for the determination of trace copper by dual-indicator catalytic kinetic spectrophotometry. Methods: In acidic media, copper ions catalyze the oxidative discoloration of methyl orange and methylene blue dual indicator. The method for the determination of trace copper was established by the relationship between the change of absorbance of catalytic system and non-catalytic system and the concentration of copper ion. Results: The content of Cu (Ⅱ) in 0.005 0 ~ 0.160 mg.L-1 was linear with the catalytic reaction rate. Conclusion: The method is convenient, accurate and reproducible. It can be used as a method for determination of trace copper (Ⅱ) in Radix Astragali.