易熔玻璃中B_2O_3的EDTA掩蔽测定方法

EDTA Masking Method to Determine B_2O_3 in Low-melting Glasses

易熔玻璃中含有大量的氧化铅及部分氧化锌,铅锌元素的存在对用酸碱滴定法测定三氧化二硼有影响。因为在滴定过程中Pb^++和Zn^++会生成氢氧化物沉淀消耗碱液,所以必须分离。而一般控制pH值的方法又很难将铝铅锌三者同时沉淀完全。

Low molting glasses contain a great amount of lead oxide and zinc oxide which interfere in the determination of B2O3 by neutralization titration. Based on the complexometric titra-tion principle, a method was proposed to determine B2O3 in low melting glasses using Ga-BDTA as a screening agent at pH=7. The B2O3 value measured by this method is in agreement with that by ion-exchange method. The result indicates that the method of determining boric oxide by using Ca-EDTA to mask lead and zinc ions is successful.