This is related to the phase transfer catalysts which are a special type of liquid-liquid extraction which is used in synthetic chemistry.
For instance nitrate anions can be transferred between water and nitrobenzene.
One way to observe this is to use a cyclic voltammetry experiment where the liquid-liquid interface is the working electrode.
This can be done by placing secondary electrodes in each phase and close to interface each phase has a reference electrode.
One phase is attached to a potentiostat[1] which is set to zero volts, while the other potentiostat is driven with a triangular wave.