GE Monitor UPC-900 Operating Instructions Manual page 89

6.3.4 Clean the pH electrode
Precautions
Clean the pH electrode
Use one of the following procedures to clean the electrode to improve the response:
Salt deposits
Dissolve the deposit by immersing the electrode first in 0.1 M HCl, then in 0.1 M NaOH,
and again in 0.1 M HCl. Each immersion is for a 5 minute period. Rinse the electrode tip
in distilled water.
Oil or grease films
Wash the electrode tip in a liquid detergent and water. If the film is known to be soluble
in a particular organic solvent, wash with this solvent. Rinse the electrode tip in distilled
water.
Protein deposits
Dissolve the deposit by immersing the electrode in a 1% pepsin solution in 0.1 M HCl for
five minutes, followed by thorough rinsing with distilled water.
If these procedures fail to rejuvenate the electrode, the problem is most likely a clogged
liquid junction.
Step
1
Monitor UPC-900 Operating Instructions 29-0567-16 AB
WARNING
Corrosive substance. NaOH is corrosive and therefore dangerous
to health. When using hazardous chemicals, avoid spillage and
wear protective glasses and other suitable Personal Protective
Equipment (PPE).
WARNING
Corrosive substance. HCl is corrosive and therefore dangerous to
health. When using hazardous chemicals, avoid spillage and wear
protective glasses and other suitable Personal Protective Equipment
(PPE).
Action
Heat a 1 M KNO solution to 60 to 80°C.
3
6 Maintenance
6.3 Cleaning
6.3.4 Clean the pH electrode
89