双氧水存在下钙-萘酚绿B体系的极谱波及分析应用

Polarographic Behavior of Calcium-Naphthol Green B Complex in the Presence of Hydrogen Peroxide and Determination of Calcium

研究了在双氧水存在下钙 萘酚绿B体系的极谱波行为及其应用。在pH 11.8的氢氧化钠溶液中 ,钙 萘酚绿B络合物于 - 0 .6 7V可产生灵敏的极谱波 ,加入双氧水后极谱波移至 - 0 .72V ,且波高明显增大。导数波高与钙离子浓度在 0 .0 1～ 3.5mg L范围内呈线性关系。研究了该波的性质及电极反应机理。证明为配位体还原的络合吸附催化波。利用拟定的方法测定了水样。

A new polarographic method for the determination of trace calcium was proposed. The complex of calcium naphthol green B can produce a sensitive polarographic wave at -0.67 V( vs .SCE) in pH11.8 NaOH solution. When hydrogen peroxide was added, the wave height increased and the peak potential moved to -0.72 V . The derivative wave height is linear with the concentration of calcium in the range of 0.01～3.5 mg/L, and detection limit is 0.006 mg/L. The adsorptive catalytic character of the wave was proved. The composition ratio of calcium naphthol green B complex was found to be 1∶1. Naphthol green B in the complex was reduced and its product then oxidized by hydrogen peroxide to its original state. A catalytic cycle was formed and the sensitivity increased obviously. The method has been successfully used to determine calcium in natural water and hair samples.