摘要
实验研究发现:在pH=4.74的NaAc-HAc缓冲溶液介质中以氨三乙酸(NTA)作活化剂,Mn(Ⅱ)可以强烈地催化高碘酸钾氧化三溴偶氮氯膦褪色的反应。通过实验确定该反应体系的最佳条件,测定催化动力学参数及催化反应的表观活化能Ea′=37.73kJ/mol,表观速率常数为k′=8.85×10-4s-1,探讨了反应机理,确立反应的速率方程()lgA0A=K?Δt?CMn(∏),由此建立一个测定痕量锰的新方法。本方法的检测限是2.3×10-9g/mL,测定范围为2.3～10.0ng/mL。该法具有较好的选择性,用于枸杞、茶叶、环境水体试样中痕量锰的测定。
A new catalytic spectrophotometric method for the determination of trace amount of manganese（Ⅱ） has been developed. The method is based on oxidation of TB-Chlorophosphonazo by potassium periodate in HAc-NaAc medium in the presence of nitric tri-acetic acid act as activator. The optimum reaction conditions are studied. The reaction rate equation is found to be： （ ）lg A0 A= K？Δt？CMn（∏） and the apparent reaction activation to be Ea′=37.73 kJ/mol,apparent reaction rate constant to be k′=8.85×10-4s-1 .The detection limit of the method is 2.3×10-9 g/mL. The linear ranges for the determination of Manganese（Ⅱ） is 0.0～10.0 ng/mL. Satisfactory results are obtained for the determination of trace Manganese（Ⅱ） in Chinese matrimony-vine , tea and water sample in environment.
关键词
分析化学
催化动力学光度法
三溴偶氮氯膦
锰
analytical chemistry catalytic
spectrophotmetry
manganese
TB-chlorophosphonazo
