在离子选择电极法中,采用加入标准法进行分析,常可减小试样组分变动的影响。目前应用较多的是一次加入标准法(借助于计算公式或Gran图)和连续加入标准法(借助于Gran图)。但是,无论是用计算公式或Gran图进行计算,均需事先测定电极的能斯特(Nernst)斜率。为了使Gran图适用于不同能斯特斜率的离子选择电极,我们曾提出用△E或ApX作图的改进的Gran图,但仍需事先测定电极的能斯特斜率。两次加入标准法是根据连续两次加入相同体积 In the ion-selective electrode method, by adding the standard method for analysis, often can reduce the impact of sample composition changes. Currently used more than once by adding the standard method (by means of formula or Gran graph) and the continuous addition of standard method (with Gran). However, whether calculated by the formula or the Granogram, the Nernst slope of the electrode must be determined in advance. In order to apply the Granogram to ion-selective electrodes with different Nernst slopes, we have proposed an improved Granogram plotted with either ΔE or ApX, but the Nernst slope of the electrode still needs to be determined beforehand. Two times to join the standard method is based on two consecutive additions to the same volume