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    毛细滴管在计滴微量滴定法中的应用及其测量不确定度的评定

    Application of Capillary Microburette to Drop-Counting Microtitrimetry and Evaluation of Its Uncertainty in Measurements

    • 摘要: 与不锈钢及玻璃相比,聚乙烯是制作毛细管微滴定管的合适材料.所制成的微滴定管应用于计滴微量滴定法中,并通过食醋中总酸度的测定,食盐中碘酸盐的测定,水的总硬度测定及水中溶解氧的测定等4种方法中的应用对其适用性作了考核,对计滴微量滴定法测定食醋的总酸度的测量不确定度作了评定.如试验数据所示,从微滴定管流出的滴定剂每滴的体积在0.01~0.02 mL之间.如果一次滴定所耗滴定剂总量在70~110滴(约1 mL)之间,上述4种测定方法所得结果的RSD值(n=6)在0.6%~1.8%之间,回收率试验的结果在99.4%~101.4%之间,食醋中总酸度测定的扩展相对不确定度评定为1.0%.此外,与常规的常量滴定法相比,用毛细滴管的计滴微量滴定法具有等同的准确度和精密度,而在方便携带,成本低廉及操作简便、快速等方面却大大优于前者.

       

      Abstract: Polyethylene among glass and stainless steel was chosen as suitable material for fabrication of the capillary burette.The feasibility was tested by its application to the drop-counting microtitration of total acidity of vinegar,iodate in table salt,total hardness of water and dissolved oxygen in water.Uncertainty in measurements of the method of determination of total acidity of vinegar was evaluated As shown by the data of experiments,the volume of each droplet of titrant from the microburette was from 0.01 to 0.02 mL.When the total amount of titrant used in a titration was in range of 70-110 drops (ca.1 mL),values of RSD′s (n=6) obtained were in the range of 0.6%-1.8% for the above mentioned determinations,and values of recovery were in the range of 99.4%-101.4%.The expanded relative uncertainty evaluated was 1.0%.It was also shown that the drop-counting microtitrimetry was equivalent with the conventional macrotitrimetry both in accuracy and precision,while the microtitrimetry using the capillary microburette showed its special feutures of portableness,more economic,more rapid and convenient in operations.

       

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