电位滴定法测定复配甜味剂中氯化物含量的不确定度评定

Evaluation of Uncertainty in Determination of Chloride Content in Compound Sweeteners by Potentiometric Titration

采用全自动电位滴定法测定复配甜味剂中食盐(以NaCl计)含量的测定方法,通过对称量、样品处理、摩尔质量、电位滴定和其他因素带入的不确定度分别进行评定,最终得到样品中食盐(以NaCl计)含量的相对标准不确定度和扩展不确定度。结果表明,复配甜味剂中食盐(以NaCl计)的含量为(10.19±0.06)%,k=2,通过对不确定度的评定,得出对采用全自动电位滴定法测定复配甜味剂中食盐(以NaCl计)含量的不确定度贡献最大的是由重复测量带入的不确定度。

The automatic potentiometric titration method is used to determine the content of table salt(calculated by NaCl)in the compound sweetener.The relative standard uncertainty and expanded uncertainty of the content of table salt(calculated by NaCl)in the sample are finally obtained by evaluating the uncertainty brought by weighing,sample treatment,molar mass,potentiometric titration and other factors.The results showed that the content of table salt(calculated by NaCl)in the compound sweetener was(10.19±0.06)%,k=2.Through the evaluation of the uncertainty,it was concluded that the most important contribution to the uncertainty of determining the content of table salt(calculated by NaCl)in the compound sweetener by automatic potentiometric titration was the uncertainty brought in by repeated measurement.