Depending on their use, the lifespan of pH probes can be very variable. Here are some tips to extend life or improve measurement accuracy.
Filling the probes with electrolyte: if the electrolyte level is too low in the electrode, it must be added using a syringe. If it is contaminated, it is better to remove it using a syringe and a needle before adding the new electrolyte.
Often the problems come from contamination of the diaphragm.
Lipid Contamination: Use detergents, solvents like ethanol, acetone, diethyl ether, strictly for a short time. Then wash the electrode with distilled water.
Contamination by carbonates and metal hydroxides: Shake the lower part of the probe in 10% HCl and wash with water.
Contamination by sulfides: Shake the lower part of the probe in 10% HCl saturated with thiourea and wash with water.
Protein contamination: Leave the probe in 0.1 M HCl containing 10 mg pepsin / ml for several hours and wash with water. If nothing helps, you can try cleaning with Sulfochromic Acid for 10 minutes and washing with distilled water with KCl added. Sulfochromic acid is very dangerous!
Notes: Prolonged exposure to distilled water should be avoided. The ion exchange zones in the glass, necessary for the generation of the signal, can be disturbed.