柠檬酸-罗丹明B体系阻抑动力学光度法测定痕量钴(Ⅱ)

Determination of trace cobalt(Ⅱ) by inhibitory kinetic spectrophotometric method of citric acid-rhodamine B system

催化动力学光度法以其灵敏高、检出限低，受到人们广泛重视。催化动力学光度法常用分析方法有催化氧化动力学光度法、催化还原动力学光度法、催化荧光光度法、阻抑动力学光度法等。催化动力学光度法其检测限都在ng·mL^-1级，通常用于痕量分析，尤其适用于痕量金属离子测定。

When in NH3·H2O-NH4 Cl （pH = 9.5）and at temperature of 80℃. the depigmentation reaction in hydrogen peroxide oxidation rhodamine B can be obviously inhibited by Cobalt （ Ⅱ）-Citrate. The best kinetic experimental conditions of catalytic inhibitory reaction were studied in this paper and the kinetic parameters were discussed, and based on this, a new method of catalytic inhibitory oxidation kinetic spectrophotometric determination of cobah （Ⅱ） was established. The logarithms of absorbency difference between non inhibitory oxidation reaction （ the absorbency is Ao ） and inhibitory oxidation reaction （ the absorbency is A ） n △A remains a good linear relationship with the mass concentration of cobalt（Ⅱ） in the range of 0 - 8.0 × 10.3 μg ·mL^-1 , and the detection limit is 2. 795×10 μ g·mL^-1. This inhibitory catalytic oxidation reaction matches pseudo first order. At temperature of 80℃, the apparent rate constant is 2.70 × 10^-4· s^-1 , and the apparent activation energy, is 43.24 kJ ·mol^-1. When applied to the determination of VB12 injection medicine, this method reslrlted with a recovery rate between 95.5% - 101.0% that met the requirement of trace analysis.