1. Determination of calcium carbonate content

The original industry standard uses acid-base backtitration to determine the main content, which is expressed in calcium carbonate. In fact, it is the determination of carbonate in the sample, calculated by calcium carbonate, indicating the main content, which can not truthfully reflect the content of calcium carbonate in the sample. GB/T 19281-2003 "Ultra-fine calcium carbonate" in the provision of the complex titration method to determine the content of calcium carbonate, in order to truly reflect the actual content of calcium carbonate in the product, the revision uses GB/T 19281-2003 "ultra-fine calcium carbonate" specified methods, that is, the use of complex titration method to determine the content of calcium carbonate, When triethanolamine was used as masking agent and pH was greater than 12, sodium calcium carboxylate was used as indicator and titrated with EDTA standard titration solution of 0.02mol/L. This method is a classical method for the determination of calcium content. By adding triethanolamine to mask the interference of iron, aluminum and other metal ions, and then eliminating the interference of Mg by adjusting the pH value greater than 12, the determination result is accurate, simple operation, and has been proved by practice.