In contrast to ISE, where the potential between two electrodes is measured at zero-current conditions, standard voltammetric polarizable systems incorporate four electrodes (sometimes reduced to two if the interface and, thus, the current are sufficiently small). Two pseudoreference electrodes made of platinum or, more often, Ag/AgCl are placed close to the liquid junction and should be small enough not to disturb the process at the interface. The second two "working" electrodes should be of considerable size and they should be positioned in line with the interface so that applied potential field lines (or current) pass perpendicularly through the interface . Such a four-electrode electrochemical cell is usually prepared by a glassblower as its commercial availability is strongly limited.