镧(Ⅲ)-8羟-基喹啉-曙红Y体系催化动力学荧光光度法测定镧汞齐中痕量镧

Determination of trace lanthanum (Ⅲ) in lanthanum amalgam by catalytic kinetic fluorometry with lanthanum(Ⅲ)-8-hydroxyquinoline-eosin Y system

在醋酸-醋酸钠缓冲溶液中,曙红Y于特定的激发波长下可以发射较强的荧光光谱,加入少量的8-羟基喹啉后,体系的荧光强度明显增强,而乳化剂OP的加入可以使荧光强度进一步加强,若在以上体系中加入痕量镧（Ⅲ）离子,荧光强度会继续加强,镧（离子在该体系中起到了催化剂的作用。据此建立了一种测定痕量镧（Ⅲ）的新体系。文中讨论了酸度、反应温度、反应时间、试剂用量及共存离子的影响,确定了实验最佳反应条件,并测定了催化反应的表观速率常数和表观活化能。方法的线性范围为0.2~1.2μg/mL,检出限为5.4×10-4μg/mL,可用于镧汞齐中痕量镧的测定。

In acetic acid-sodium acetate buffer solution,eosin Y could emit a stronger fluorescence spectrum at particular excitation wavelength.The fluorescence intensity of this system would be enhanced obviously when a little 8-hydroxyquinoline was added in the solution,while the addition of emulsifier OP could further enhance the fluorescence intensity.If trace lanthanum ion Ⅲ were added in this above-mentioned system,the fluorescence intensity would continue to be strengthened,which indicated that lanthanum ion Ⅲ played a role of catalyst.Based on this phenomenon,a new system for determination of trace lanthanum was established.In this paper,the influence factors were discussed,such as acidity,reaction temperature and time,reagents dosage and coexisting ions.The optimum reaction conditions,as well as the apparent rate constant and apparent activation energy,were determined.The linear range was 0.2-1.2 μg/mL,and the detection limit was 5.4×10-4 μg/mL.The proposed method could be applied to the determination of trace lanthanum in lanthanum amalgam.