A program for the graphical evaluation of pKa values from spectrophotometric data

A program for the graphical calculation of dissociation constants from spectrophotometric data is described. The program can treat systems which have up to two protonation steps. It can run on PC microcomputers with at least 256 Kb RAM and a monochrome graphics card or superior. The program consists of three blocks. In the first, graphic editing of the data files is performed. In the second, the treatment of systems with only one pKa is carried out. The methods of Stentrom-Goldsmith, Sommer and normalized variables are implemented. In the third, the treatment of systems with two protonation steps allows the simultaneous calculation of the two pKa values using the normalized variable + parameter and the projection strip methods.