EDTA法测定牛奶中钙含量及条件探讨

To Investigate the Calcium Content in Milk and the Conditions for EDTA Determination

测定牛奶中的钙含量时，在PH=9～10的弱碱性条件下，以铬蓝黑R为指示剂，用EDTA滴定经盐酸溶液溶解过的牛奶钙沉淀物。从蒸发加热方式、灰化条件、过滤方式等方面进行备件探讨，分析不同实验条件对测定结果的影响。结果表明：使用可调式电炉加热并不断搅拌为最佳蒸发加热方式，灰化时间为3小时、灰化温度为580℃时为最佳灰化条件，使用离心机分离含钙沉淀比使用滤纸过滤含钙沉淀所得的钙含量要高，原因是滤纸过滤操作步骤较繁琐，每步均损失一定量的钙成分，导致最后总体钙含量较低。

The determination of the calcium content of milk, alkaline conditions in the PH = 9 to 10, Eriochrome blue black R is a chromium indicator, titrate with EDTA dissolved by hydrochloric acid solution had milk calcium precipitates. Conditions of conduct in terms of evaporation heating, ashing conditions, filtration methods to analyze the effect of different experimental conditions on the measurement results. The results showed that： the use of electric heating and the adjustable constant stirring to evaporate the best heating method, ashing time of 3 hours, the ashing temperature was 580℃ ashing when optimal conditions using centrifuge using a filter paper over precipitated calcium the resulting calcium precipitate calcium content is higher, because the filter paper is relatively complex procedure, the loss of a certain amount of each step are calcium component, resulting in a lower final calcium content in general.