GE AKTApure, User Manual, Page: 293 / 522

7.6.7 Clean the pH electrode
Maintenance interval
Clean the pH electrode when required. The pH electrode can be cleaned either when it is installed in
the pH valve or when it has been removed. The pH electrode has a limited longevity and should be
replaced every six months or when the response time is slow, see Section 7.5.2 Replace the pH electrode,
on page 275. After cleaning has been performed, re-calibrate the pH monitor, see Section 7.7.1 Calibrate
the pH monitor, on page 303.
Required material
The following materials are required:
• Syringe, 25-30 ml
• Distilled water
• 0.1 M HCl and 0.1 M NaOH
or
• Liquid detergent
or
• 1% pepsin solution in 0.1 M HCl
or
• 1 M KNO
3
Cleaning agents
Clean the pH electrode using one of the following procedures:
Salt deposits
Dissolve the deposits by immersing the electrode for a five minute period in each of the following solu-
tions:
• 0.1 M HCl
• 0.1 M NaOH
• 0.1 M HCl
Rinse the electrode tip in distilled water between each solution.
Oil or grease films
Wash the electrode tip in liquid detergent and water. If the films are 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 solution of 1% pepsin in 0.1 M HCl for five minutes,
followed by thorough rinsing with distilled water.
ÄKTA pure User Manual 29119969 AB 293
7 Maintenance
7.6 Maintenance when required
7.6.7 Clean the pH electrode