碳酸盐pH基准测量方法的国际比对

International Comparison of Carbonate pH Primary Measurement Method

简述了我国水溶液酸度(pH)基准3次参加碳酸盐pH测量国际比对的过程。在2006年CCQM.K18和2007年CCQM.K18.1比对中发现基准存在系统误差。经分析,认为这个负的系统误差是由于基准Harned-Cell电池的结构造成电极电势持续飘移,采用斜率倒推得到的平衡电势偏低而产生的。2009年基准进行了改造完善,采用了新的Harned-Cell电池结构,并在2020年APMP.QM-K18.2016国际比对中取得了国际等效一致,等效度DoE(d_(i),U(d_(i)))为DoE(−0.0014,0.0030)。

The process of the Chinese aqueous solution acidity(pH)primary standard participating in three international comparisons of carbonate pH measurements is briefly described.A systematic error in the benchmark was found in the 2006 CCQM.K18 and 2007 CCQM.K18.1 comparisons.It was concluded that the negative systematic error was caused by the continuous drift of the electrode potential due to the structure of the primary standard’s Harned-Cell and the low equilibrium potential obtained by using slope inversion.In 2009,the pH primary standard device was modified and improved with a new Harned-Cell structure,and in the international comparison of APMP.QM-K18.2016 in 2020,the international equivalence agreement was achieved,and the degree of equivalent DoE(d_(i),U(d_(i)))was DoE(−0.0014,0.0030).