酸碱指示剂滴定法测定白酒中总酸含量的不确定度评定

Evaluation of the Uncertainty in the Determination of Total Acids in Baijiu by Acid-Base Indicator Titration

通过采用国家标准GB 12456—2021中的第一法对白酒总酸进行了测定,并对该检测结果的不确定度进行了评定。经评定,该检测过程中的不确定度来源主要有测量的重复性、标准滴定溶液浓度、滴定体积、稀释倍数、取样体积以及换算系数,白酒中总酸的检测不确定度结果为(0.88±0.01)g/L,k=2。不确定度贡献率为:测量重复性10.0%,标准滴定溶液浓度4.2%,滴定体积20.5%,,试液稀释倍数43.1%,取样体积21.2%,换算系数1.0%。

The total acids in Baijiu was determined according to the first method in the national standard GB 12456-2021,and the un-certainty of the testing result was evaluated.It was found that the main uncertainty sources included the measurement repeatability,the titrant concentration,the titration volume,the dilution ratio,the sampling volume and the conversion coefficient.The uncertainty of the testing result was(0.88±0.01)g/L,k=2.The contribution of each uncertainty source was as follows:the measurement repeat-ability 10.0%,the titrant concentration 4.2%,the titration volume 20.5%,the dilution ratio 43.1%,the sampling volume 21.2%,and the conversion coefficient 1.0%.