高钙低镁体系中钙镁测定方法的改进研究

An Improvement Research of Calcium and Magnesium Determination in High Calcium and Low Magnesium System

中文关键词:  EDTA  加镁  终点变色灵敏度  回收率

英文关键词:EDTA  Adding magnesium  Color sensitivity of the titration end point  Recovery rate

中文摘要:

      EDTA络合滴定法是应用范围比较广的传统方法，但该方法对样品中钙镁摩尔比的适用范围约为1：10-10：1，时于超过该范围的钙镁比样品测定的准确度会有所下降；传统EDTA络合指示剂滴定法测定高钙低镁体系中钙镁含量时，终点不易判断，测定结果平行性差，甚至出现钙镁总量小于钙量的情况。通过往样品中加入一定量Mg’标准溶液的方法，改善了滴定反应效果。结果表明，Mg^2＋的加入能明显提高滴定终点变色灵敏度。加标回收试验表明，镁的回收率达到99．96％，钙的回收率达到99．40％。该方法准确度高，操作简单，适用性强。

英文摘要:

      When determine the contents of Calcium and Magnesium with the way of Traditional EDTA ti- tration in high calcium and low magnesium system, the destination is not easy to determine, the sparallelity of determination result is poor and even the content of Ca and Mg is less than the content of Ca in the sample. In this paper, some standard solution of Magnesium was added to the system, and improve the ti- tration results. The results show that： the adding of Magnesium can improve the color sensitivity of the ti- tration end point. Spiked recovery tests showed that the recovery rate of magnesium is about 100% ,calci- um recovery rate is 99. 40%. The method is accurate, simple, and applicability.