A Determination Method by Integrating a Potentiometric Titration Curve

Abstract

A determination method based on the definite integral of a titration curve was applied to a potentiometric titration whose experimental curve does not show a sharp inflection point or a symmetric shape.
If the area, A, of the titration curve surrounded with E=Ea, E=Eb, and E-axis is measured, the concentration of the sample, cz, is given by the following relationship,
where V is the volume of the added titrant, E is the potential of an ion-selective electrode, Ex and Eb are set potentials chosen, and P and Q are constants and dependent upon both Ea and Eb. It was shown theoretically that the above equation was applicable to precipitation, complexformation, and acid-base titrations.
This method could be applied satisfactorily to F^--Ca²⁺, Ag^--CrO₄^2-, Ag⁺-edta^4-, and β-alanineNaOH systems with almost the same accuracy and precision as those obtainable with the potentiostatic method previously reported.