Life glass membrane electrodes

Glass-membrane electrodes have a limited life, usually 1-2 yr if cared for. The glass becomes slowly weakened by contact with sample and standardizing solutions until it decomposes or shatters. 

A regular maintenance schedule and proper storage of the pH electrode ensures proper performance, helps extend the life of the electrode, and avoids the cost of replacements. On a weekly basis the electrodes should be inspected for scratches, cracks, deposits, and membrane-junction deposits. The reference chamber of refillable electrodes should be drained, flushed with fresh filling solution, and refilled. (Note The chamber should only be filled to about 75 to 80% of capacity, to allow expansion during temperature change.) This maintenance procedure will keep the electrode ready to use and improve the lifetime of the electrode. A standard glass electrode in normal use can last for up to two years. 

Glass electrodes exhibit erratic behavior in the presence of only 10 m hydrofluoric acid (HF) and therefore are not normally used below pH 6. Also, in low pH solutions containing HF, the glass electrode life is severely limited because of HF attack on the glass membrane. 

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