pH gradients generated by polyprotic buffers. I. Theory and computer simulation

This paper presents the general equations for computing pH, dissociation coefficients, buffering power and ionic strength of pure polyelectrolyte solutions (polyacids, polybases and zwitterionic species with any number of dissociable groups) and mixtures of any number of these species. A program has been written for simulating the behaviour of mixtures containing up to 50 species (including buffers and titrants), each of them with up to 10 dissociable groups. This allowed one to check the equations with the available data on a few oligoprotic species.