Take a look at the book EXCEL for chemists by E. Joseph Billo pg. 349-356. This way you can use EXCEL to calculate your stability constants using NNLS analysis. If you use Computational Methods for the determination of Formation Constants edited by D. J. Leggett it gives you the written PSEQUAD program for input in FORTRAN. If you want a simpler method contact [email protected]. and ask about a copy of Hyperquad2008

I guess you may get n number of sigmoidal curve, try to extend every the mid point of individual cure is meet at particular buffer ranges. By this way u will find out stability constant by applying some differential equation.

Take a look at the book EXCEL for chemists by E. Joseph Billo pg. 349-356. This way you can use EXCEL to calculate your stability constants using NNLS analysis. If you use Computational Methods for the determination of Formation Constants edited by D. J. Leggett it gives you the written PSEQUAD program for input in FORTRAN. If you want a simpler method contact [email protected]. and ask about a copy of Hyperquad2008

If you still require such software, there is one, recently developed and free of charge, KEV (https://k-ev.org/). Preliminary e-mail registration is required though.

I think the best software, to determine the stability constants with full statistical data considering all the formation constants, is "MINIQUAD".