General mathematical model for the steady state in isotachophoresis : calculation of the effective mobility of terminating H+ ions and two-buffer electrolyte systems

An extension of the mathematical model for the steady state in isotachophoresis is given for the calculation of the effective mobility of terminating H+ ions and two-buffer electrolyte systems. The model is verified using the specific zone resistance at 25°C (SZR2) as an experimental parameter for several leading electrolytes with one and two buffering counter ionic species. The theoretically calculated SZR25 values show good agreement with the experimentally obtained values. The "enforced" migration of Al3+ in a two-buffer electrolyte system with acetic and a-hydroxyisobutyric acid as counter ionic species can be understood by comparing experimental and calculated data, using this model.