Influence of the electrode compartment separating membranes on continuous flow electrophoresis

The influence of the ion permeable diaphragms, separating the electrode compartments of continuous flow electrophoresis chambers from the separation space, are described in detail. A set of equations is derived from a simplified phenomenological model of the ion transport across media boundaries. These equations are useful to predict the magnitude of concentration changes near the membranes due to the electrophoretic ion transport. Adaption to any CFE geometry, membrane material and electrolyte system is possible with only a few measurements, which yield the transference number difference as a characteristic transport property of the membrane material for a special electrolyte. The validity of the equations is checked by experiments. Local electric field strength and local conductivity are measured with a potential gradient-conductivity scanner developed in our laboratory. This device yields data on the dynamics of the concentration changes.