Low impedance coaxial K+ selective microelectrodes.

A procedure for preparing coaxial K+ selective microelectrodes with a low longitudinal resistance (Re) of the liquid ion exchanger selective barrel is described. The low resistance was attained by inserting another microelectrode filled with 0.5 mol . 1-1 KCl into the ion-exchanger column (Corning 477317). The lower longitudinal resistance decreases the noise level and consequently increases the resolving power five times. This modification makes it possible to measure small and rapid K+ concentration changes.