Solid state reference microelectrodes. The confusion I have is that chloride salts are needed to stabilize the solid state reference microelectrodes, but the chloride salts are considered a problem again when the Cl salt concentration is high.
It is often found in microelectrochemistry that AgCl coated on Ag wire is used as quasi-reference electrode instead a reference electrode. In this way, one can get rid of the Cl-.
If the concentration of Cl- is high, then AgCl + Cl- = AgCl2- is formed ( a complex ion, soluble). Any low concentration of Cl- is good for a stable REF electrode.
With AgCl, you need to have ample amount of Cl ion in the filling solution to make sure that the reaction AgCl Ag+ + Cl- (i.e., Cl- ion falls off the surface) won't happen.
Thus NaCl or KCl will do for this purpose, But to minimize liquid junction potential (caused by non-equal mobility of individual ions), concentrated KCl appears to be the ideal solution because K+ and Cl- have approximate equal mobilities. PS: Na+ ion moves much slower than Cl- does
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