Abstract
Purities of some standard reagents for volumetric analysis were determined directly by the coulometric titration method. The apparatus used was nearly the same as that in the previous paper {Yoshimori et al.: This Journal, 15, 1234 (1966)}, but the end points were located by a pH meter with glass electrode.
A little lower results were obtained for standard potassium biphthalate reagents, with coefficient of variation about 0.034%. Results obtained for the standard samples of sulfamic acid and sodium carbonate were satisfactorily coincided with their certificated values. Coefficients of variation for them were about 0.017% and 0.044%, respectively.
It seems that these differences in coefficients of variation depend largely on the magnitude of change in pH through the end points.
