可见光光谱滴定法测定水中总硬度

Determination of Total Hardness in Water by Visible Spectral Titration

提出了可见光光谱滴定法测定水中总硬度的方法。在整个滴定过程采用颜色真实测量体系替代人的感官判定,建立了光谱计量参数与试剂量的色变滴定曲线,用曲线上的突变峰标识滴定终点或结构变化点。可见光光谱滴定法可以克服感官滴定存在色评价条件不统一、操作人员个体生理条件不一致、无法量值溯源等困难,能实现测定的自动化。上述方法用于测定水质总硬度标准样品,结果显示测定值均在标准样品认定值的不确定度范围内。按照标准加入法对实际样品进行回收试验,回收率为99.7%~101%。分别采用可见光光谱滴定法和目视滴定法[即乙二胺四乙酸(EDTA)络合滴定法]测定8种水体样品的总硬度,配对t检验结果表明两种方法的测定结果无显著性差异。

A method of determination of total hardness in water by visible spectral titration was proposed.During the entire titration process,the real color measurement system was used to replace human sensory judgment,and the color change titration curve was established between spectral measurement parameters and reagent quantity.The abrupt peak on the curve was used to identify the titration endpoint or structural change point.Visible spectral titration could overcome the difficulties of sensory titration,such as the disunity of color evaluation conditions,the inconsistency of individual physiological conditions of operators,and the inability to trace the value,and it could realize the automation of measurement.The above method was applied to determination of total hardness of water quality standard samples,and it was shown that the determined values were within the uncertainty range of the certified values of the standard samples.Test for recovery was made on the actual samples by the standard addition method,giving results in the range of 99.7%-101%.The total hardness of 8 water samples was determined by visible spectral titration and visual titration(EDTA complexometric titration),respectively.As found by the paired t-test results,there was no significant difference in the determination results between the two methods.