Electrolyte for salt bridges

Choice of electrolyte for salt bridges and reference electrodes. Many of the difficulties encountered in potentiometric measurements can be attributed to erratic or drifting junction potentials caused by clogged junctions. Certain elementary rules should be observed in choosing the filling solution for a salt bridge or reference electrode, particularly when they will be used in organic solvents or solutions that are only partially aqueous. 

Very often it is imperative to prevent any contact between the analyte solution and the reference electrolyte solution, and this can be achieved by an additional salt bridge (see Fig. III.2.7). The electrolyte solution in the salt bridge has to be chosen so that it will not influence the measurement. It must be tolerated by both the reference electrolyte solution and the analyte solution. The most important electrolytes for salt bridges are potassium nitrate, potassium chloride, sodium sulphate, or ammonium nitrate solutions. 

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