Linear regression analysis of potentiometric titration data for asymmetric redox reactions

A statistical method is proposed for treating potentiometric titration curves for homogeneous asymmetric redox reactions. The method is based on the use of a mathematical model for the transformation of the branch of a titration curve in the region of potentials of a reversible redox couple into a linear regression characteristic whose slope numerically coincides with the equivalent titrant volume to an accuracy of the LS estimation. The method was verified in the model titrimetric system Mohr's salt-K₂Cr₂O₇ and used for determining tellurium in an individual solution, in a semiconductor CdTe alloy, and in a CdTe ceramic. The random error in the estimation of the equivalence point by the data of a separate titration of 0.1-0.01 M solutions does not exceed 0.3%. In the case of titration of a 0.001 M solution, this error increases to 1.2%. The value of RSD varies from 0.06 to 0.7%.