锌镉还原法测定海水硝酸盐的改进

Improvement of Zinc-cadmium Reduction Method for Determination of Nitrate in Seawater

提出在锌镉法中添加含氨的氯化铵溶液,称铵锌镉还原法,其还原率94.3%,精密度2.0%,比锌镉法还原率和精密度高,无盐效应,又有锌镉法操作简便之优点。铵锌镉法反应机理:由于氨使Zn2+形成络合物,NH4+电离出H+,二者使NO3-还原更完全。

The so-called ammonium-zinc-cadmium method originates from the zinc-cadmium method,in which ammonia chloride solution（with ammonia included） is added and involved as it is suggested in the paper.By means of the new method,the reduction rate is about 94.3% and its precision is about 2.0%,being much better than those of the zinc-cadmium method.And no salt effect results from the reduction.This new method with its simple operational procedure can be used the same advantageously as the zinc-cadmium method.The reduction mechanism of the new method is that the ammonia inclusion makes Zn2＋ form the complex,and H＋ is ionized from NH＋4.The both is helpful to better complete the NO-3 reduction.