采用电位滴定法,用盐酸标准溶液作为滴定剂,测定石灰中有效氧化钙含量。优化的滴定条件为:① 滴定终点pH为7.00;② 最大馈液速率10 mL·min-1;③ 最小馈液速率100 μL·min-1;④ 滞后时间5 s;⑤ 搅拌时间1 min。方法用于石灰样品分析,测定值与手工滴定法测定值相符,相对标准偏差(n=5)在0.10%~0.19%之间。

Content of available calcium oxide in lime was determined by potentiometric titration using HCl standard solution as titrant. Conditions of titration were optimized and given as follow: ① acidity at endpoint of titration: pH 7.00; ② maximum rate of titration: 10 mL·min-1; ③ minimum rate of titration: 100 μL·min-1; ④ delay time: 5 s. The proposed method was applied to the analysis of lime sample, and the results obtained were checked quite well with those obtained by manual titration. Values of RSD′s (n=5) were found in the range of 0.10%-0.19%.