Storage of Electrodes

Since the pH measurement is dependent on a hydrated glass bulb and a free-flowing junction from the reference electrode, keeping both electrodes wet is vital. 

In order to provide a fast-responding and low junction potential reference electrode, the junction must remain unclogged with low resistance and with flow of filling solution. If the junction is allowed to dry, some sample particles or precipitate may be difficult to remove from the junction by soaking. 

The combination electrode can be stored in a combination of the recommended glass and reference storage solutions that is, pH 4 buffer with a few drops of saturated potassium chloride added. 

Since a glass or reference electrode may vary in the potential that it produces in a given solution, standard solutions are required in order to equate different electrode pairs at a given pH. These standard solutions are referred to as buffers. As the name implies, these solutions have the ability to resist change in pH due to dilution or contamination. 

The pH of an unknown solution is determined by comparison to an accepted standard solution. In other words, the pH(A ) for an unknown solution can be determined by relating the potential Ej. obtained with a pair of electrodes in the unknown solution to the potential obtained in an accepted standard of pH(5) if the electrode response S (slope) is known. The pH meter displays this difference observing the expression 

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