Nonlinear regression program DCMINOPT is introduced for numerical analysis of a set of {A, pH} data expressing a dependence of absorbance of a mixture of variously protonated light-absorbing species L, LH,..., LHR on pH. Efficiency of the program has been examined on simulated A-pH data corrupted with artificial (generated) errors namely for a case of closely overlapping protonation equilibria. An accuracy and precision of parameters estimates have been examined and compared with those determined by another three standard algorithms DCFIT, DCMINUIT and PSEQUAD. Goodness-of-fit test brings various regression diagnostics, 3D-plots and statistical measures enabling to test and prove a reliability of a regression process and accuracy and precision of parameter estimates. © 1993 Springer-Verlag.
