ABSTRACT
The fabrication of ion-selective electrodes suitable for use in the intracellular space or in small extracellular spaces requires techniques different from those employed when making large dip-cast electrodes. The problem centres around introducing a small amount of ion-selective ligand into the tip of a micro-pipette and filling the remainder with a suitable ionic, filling solution. To achieve this it is necessary to render the inside of the pipette hydrophobic to allow the oily ion-selective ligand solution to fill the tip and prevent an electrical shunt via an aqueous layer on the inner wall of the pipette. Virtually every laboratory has different techniques for making such electrodes. The following procedure has been used in our laboratory for Ca2+, Mg2+, Na+, K+ and H+ -sensitive micro-electrodes.
