基于电位滴定法的海水总碱度分析仪校准方法研究

Study on the Calibration Method of Seawater Total Alkalinity Analyzer Based on Potentiometric Titration

本文探索了基于电位滴定原理的海水总碱度分析仪的校准方法。利用称量法可以实现进样管容量误差的校准,盐酸容量误差小于等于0.1%;分别利用海水总碱度标准样品和标准物质碳酸钠作为参考标准物质进行校准方法研究,实验结果表明海水总碱度标准样品和碳酸钠两种参考标准物质均可用来校准海水总碱度分析仪,相对误差绝对值均小于0.1%,首次进行了碳酸钠溶液的稳定性测试,24 h后溶液更稳定;校准工作曲线的斜率约为1.0027,说明总碱度测量值与标准值之间的一致性良好;从不确定度分析结果来看,采用海水总碱度标准样品校准的不确定度为0.22%,碳酸钠配制的总碱度溶液的不确定度偏大,为0.30%;但从经济角度来看,碳酸钠更具有适用性。

The article explores the calibration method for the seawater total alkalinity analyzer based on the principle of potentiometric titration.The weighing method was used to calibrate the volume error of the injection tube,and the capacity error of the HCl injection tube is less than or equal to 0.1%.The results showed that the reference materials of total alkalinity of seawater and sodium carbonate can be used to calibrate the total alkalinity analyzer of seawater,and the absolute relative error is less than 0.1%.For the first time,the stability test of sodium carbonate and artificial seawater after preparation was 24 h.The slope of the two calibration curve was about 1.0027,which shows that the consistency between the total basicity measurement value and the standard value was good.The uncertainty of calibration with total alkalinity standard sample of seawater was 0.22%,and the uncertainty of sodium carbonate solution was 0.30%,but from the economic point,sodium carbonate is more suitable.