摘要
交流示波极谱滴定用于矽石分析已有多篇报导(1,2)。本文对钙镁连续滴定进行了初步探讨,认为以Zn^(++)离子为切口指示剂,在pH=10,NH_3+NH_4浓度为0.1M时,用EGTA滴定钙;再向溶液加入1:1氨水,使NH_3+NH_4^+浓度增加到1.2M左右,pH=11,用CYDTA滴定镁,可实现钙镁连续测定。不同比例的钙镁含量在10mg以内,测定结果的相对误差<±5％。本方法可用于碳酸盐、硅酸盐中钙镁测定。
Alternating oscilloscope polarographic titration appling to ore analysis has been reported in previous literatures. The present writing makes a primary discussion on the calcium and magnesium continuous titration. According to the authors, it taking Zn^(2+) ion as incision indicator, when pH=10, concentration of NH_3+NH_4^+=0.1 M,using EGTA to titrate calcium, then adding 1:1 aqua ammoniac into the solution making the concentration of NH_3+NH_4^+ about 1.2M,pH=11, and using CYDTA to titrate magnesium, the continuous determination of calcium and magnesium will be possible. If the concentration of calcium and magnesium of different ratio is within 10mg, the ralative error of the results will be less than+5%. This method can be used to determine the calcium and magnesium in carbonate and silicate.
