Determination of equilibrium parameters by minimization of an extended sum of squares.

A method is proposed for the evaluation of equilibrium parameters from potentiometric data, in which all the sources of random error are taken into account. This means including in the minimized sum the residuals in all the quantities subject to error (titrant volume, emf, parameters of composition of the titrant and titrand, parameters of electrode characteristics, and equilibrium constants known from other experiments). The method of preparation of the solutions is represented by a directed, acyclic graph which allows consideration of the sources of error connected with the composition of the solutions, and avoidance of inconsistency in the composition characteristics. Numerical examples are presented.