Evaluation of formation constants, molar absorptivities of metal complexes, and protonation constants of acids by nonlinear curve fitting using microsoft excel solver and user-defined function

A nonlinear curve fitting using Microsoft Excel Solver and user-defined fun ction is described for the evaluation of formation constants and molar abso rptivities of metal complexes from spectrophotometric data and evaluation o f protonation constants of acids from potentiometric data. The procedure wa s applied to the spectrophotometric data of ML and ML2 complexes and potent iometric data of HL and H2L acids. The obtained results were compared with those of available packages. The proposed procedure is simple and user frie ndly. In addition, dynamic displaying of the iterative calculation and sear ch process, complete control of modeling processes by the user, make the pr ocedure an ideal tool for the evaluation of important parameters such as fo rmation constants and protonation constants. (C) 1999 Academic Press.