A liquid ion-exchanger alternative to KCl for filling intracellular reference microelectrodes.

We have developed a filling solution for silanised microelectrodes consisting of potassium tetrakis (p-chlorophenyl) borate in octanol. Microelectrodes filled with this reference liquid ion-exchanger (RLIE) have equal selectivities to Na and K, and give the same membrane potential as do KCl-filled microelectrodes. The RLIE microelectrodes are more stable, less damaging to the cell membrane and do not leak Cl- ions. Their high resistance, however, makes them unsuitable for recording rapid potential changes or for passing current.