催化电位滴定法测定奶粉中微量锌

Determination of trace zinc in milk powders by catalytic potential titration

报道了一种以氨三乙酸(NTA,活化剂)存在下锰(Ⅱ)催化KIO4氧化甲基紫的反应指示滴定终点,自制的甲基紫选择性电极为指示电极,用催化电位滴定法测定奶粉中微量锌的新方法。将该方法用于奶粉中锌的测定,结果与火焰原子吸收光谱法一致,样品平均回收率为99.0%,RSD为1.1%。

A new method of catalytic potential titration for the determination of trace zinc(Ⅱ) by using a methyl violet ion selective electrode was proposed. It was based on the catalytic effect of manganese(Ⅱ) on the oxidation of methyl violet(MV) by potassium periodate in the presence of nitrilotriacetic acid(NTA). It was applied to the determination of zinc(Ⅱ) in the milk powder samples. The determination results agreed with those achieved by atomic absorption spectrometry. The average recovery of sample was 99.0%, the relative standard deviation was 1.1%.