Patent ID: 7264701

Claim:
In a reference electrode assembly having an internal electrode of a silver/silver chloride composition, immersed in an internal filling solution and a liquid junction, comprising a first portion and a second portion, the improvement comprising: an inner housing having a wall surrounding the internal electrode and sealed to the internal electrode at a first end of the inner housing via an adhesive applied to the first portion of the internal electrode and/or the wall surrounding the first portion of the internal electrode and open at a second end of the inner housing, wherein the inner housing is a heat shrinkable tube and the inner housing wall is immersed in the internal filling solution and blocks the internal filling solution egress to internal electrode to only the open second end of the inner housing; an inorganic cation exchanger material positioned adjacent the second portion of the internal electrode located at an edge of an end of the internal electrode within the inner housing such that the inorganic cation exchanger material only contacts the internal electrode at the second portion of the internal electrode whereby any dissolved silver ions and chloro complex-ions interacting with the inorganic cation exchanger material are trapped by the inorganic cation exchanger material; and a first porous ceramic member is sealed to the inner housing between the inorganic cation exchanger material and the second open end, the ceramic member has pore sizes for preventing diffusion of the silver ions and chloro complex-ions into the internal filling solution.