Cleaning of the reference junction
It's not only the glass membrane of the pH electrode that require frequent cleaning. Reference junction fouling or plugging remains the primary challenge to pH measurement
in dirty applications.
Clogged reference junction treatment:
It's recommended to remove the electrolyte and replaced with fresh electrolyte. The electrode should then be heated to 60-80°C in 3M KCl and allowed to cool in the same solution for approximately 10 minutes. Rinse and put into a pH 4 buffer for at least 1/2 hour.