Association constants of 1:1 and 2:1 molecular complexes from spectrophotometric data; experimental design and reliability of the parameters

Abstract

Principles for the design of an experiment for the determination of association constants (K₁,K₂) and molar extinction coefficients (ε₁,ε₂) for molecular complexes of 2:1 stoicheiometry are discussed. The method employed is based on the maximization of the determinant of the information matrix |X′X| and is of general validity. It is shown that the reliability of a parameter depends on two independent factors: the available experimental apparatus and the experimental design (i.e. how the initial concentrations of the reagents are chosen). The correlations between parameters and to some extent the convergence of the routine of minimization are also dependent on the experimental design.