A glass-membrane pH microelectrode.

By miniaturizing the original MacInnes and Dole glass-membrane pH electrode a new pH microelectrode has been developed. The technique developed utilizes the tip of a high electrical resistance glass pipet that can be sealed with a thin membrane of H⁺-sensitive glass. Single-barreled electrodes have been made with tip diameters ranging from 1.5 to 100 μm and double-barreled electrodes with tip diameters from 2 to 28 μm. The glass-membrane pH microelectrode provided a means for sensing the pH of biological solutions with an electrode having theoretical slope and tip configurational control. The most unique characteristics of the electrode were: the pH sensing surface was quite small, the tip diameter could be controlled, and the problem of electrode insulation was eliminated.