EGTA滴定法快速测定碳酸钙中CaCO3

Fast Determination of CaCO3 in Calcium Carbonate by EGTA Titrimetric Method

利用CaCO3易溶解于稀醋酸而其它钙盐不被溶解的原理，用稀醋酸溶解试样，过滤与其它不被溶解的钙盐及物质分离。滤液在三乙醇胺掩蔽剂存在下，加入氢氧化钾调节溶液PH≥12．5，以钙磺绿素一百里香酚酞为指示剂，用EGTA标准溶液滴定至绿色荧光消失变紫红色为终点，借此测定CaCO3的百分含量。

Based on the principle of CaCO3 being liable to dissolve in dilute acetic acid while other calcium salts not, the sample, after dissolved in dilute acetic acid, filtered is broken away from other not dissolved calcium salts or substances. To the filtrate, with the presence of the masking agent triethanolamine, potassium hydroxide is added to adjust the solution at PH 〉t 12, 5 ,with calcein-thymic phenolphthalein as an indicator,the standard EGTA solution is used to titrate till green fluorescence turns aubergine,by which the content of CaCO3 is determined.