自动电位滴定仪应用于地下水六项指标的连续滴定

Application of Automatic Potentiometric Titrator in Continuous Titration of Six Indices in Groundwater

地下水中六项指标(pH、总碱度、氯离子、钙离子、镁离子及硫酸根)的分析需要对每个指标单独进行取样检测,步骤繁琐且效率较低。同时总碱度、氯离子、钙离子、镁离子及硫酸根通常采用手动目视滴定,检测结果存在人为操作误差,精密度和准确度相对较差。本文建立了准确快速测定地下水中六项指标的分析方法,只需2次取样,采用自动电位滴定仪自动判定终点,加液器可精确控制标准溶液加入量至0. 1μL,并且通过调整检测顺序、溶液酸度和加入掩蔽剂的方法消除相互干扰。本方法的加标回收率为93. 5%～120. 0%,相对标准偏差(RSD,n=10)为0. 18%～11. 33%。电位滴定法得到的数据相比标准方法的平行性更好,尤其是当所测定水样较为浑浊或者有颜色时测定数据更稳定。

BACKGROUND:The analysis of six indices(pH,total alkalinity,chloride ion,calcium ion,magnesium ion and sulfate radical)in underground water needed to be sampled separately for each index.The steps were tedious with low efficiency.Furthermore,the total alkalinity,chlorine ion,calcium ion,magnesium ion and sulfate radical usually used manual visual titration,resulting in manual operation error,poor precision,and inaccuracy.OBJECTIVES:To establish an accurate and rapid method for the analysis of six indices in underground water.METHODS:The method established and described in this paper only needed two samples and the Automatic Potentiometric Titrator could determine the end point automatically.The Automatic Potentiometric Titrator could accurately control the addition of standard solution to 0.1μL,and eliminate mutual interference by adjusting the detection order,acidity and the addition of a masking agent.RESULTS:The recoveries of this method are 93.5%-120.0%,and the relative standard deviations(RSDs,n=10)are 0.18%-11.33%.CONCLUSIONS:The results obtained by potentiometric titration had better parallelism and stability,especially when the measured water samples were more turbid or colored.