The maintenance and care of titration electrodes includes proper storage, refilling with the correct electrolyte and, if necessary, cleaning the electrode.
Which solution do I use to refill and store the electrode?
The maintenance and care of an electrode are decisively influenced by its type. An electrode with liquid electrolyte must also be topped up, otherwise sample solution can be pressed into the electrode if the electrolyte level is too low. In extreme cases, this can poison the electrode's reference system and render it unusable.
The electrolyte depends on the type of electrode. For pH and redox combination electrodes, this is a KCl solution with a concentration of 3 mol/L. For silver combination electrodes, a KNO3 solution 2 mol/L with a small addition of 0.001 mol/L KCl. For pH electrodes for non-aqueous titrations, the electrolyte solution consists of either LiCl/ethanol or LiCl/glacial acetic acid 1.5 mol/L.
With a low-maintenance electrode with gel electrolyte or an electrode with pH glass as a "reference system" (AgCl 62 RG, Pt 62 RG etc.) and with measuring electrodes, refilling is not necessary.
The electrolyte solutions can also always be used as a storage solution. You can also use distilled water for the RG electrodes.
For pH electrodes, there is also a special storage solution L 9114, in which something is added to the KCl electrolyte.
How to clean the titration electrode?
All electrodes with glass and metal sensor can be cleaned according to the following scheme:
- Carefully wipe off deposits on the glass membrane with a damp cloth.
- Rinse grease/oil with alcohol or water containing detergent.
- Remove proteins with hydrochloric acid pepsin solution L 5104. Always rinse with distilled water afterwards. Diluted hydrochloric acid (e.g. HCl 1 mol/L) can also be used as an alternative to the hydrochloric acid pepsin solution.
The following instructions for individual electrodes must be observed:
- Never wipe electrodes with platinum diaphragms with a cloth. Only ever rinse with a solution.
- Blank silver and platinum electrodes with a pin sensor such as Ag 62 IDS, Ag 6280, Pt 62 or Pt 62 and all double platinum electrodes such as KF 1100, KF 1150 and Pt 1200 can also be cleaned with an abrasive agent. Always rinse with distilled water afterwards.
Caution:
Never grind down Pt/Ag electrodes with a ring sensor such as Ag 62 RG, AgCl 62 RG or Pt 62 RG!
Storage and cleaning of ISE:
ISE should always be stored dry.
Only clean the electrodes with PVC membrane such as TEN 1100 and Ca 1100 PLH with an aqueous (max. 5 % alcohol) solution. Never clean electrodes with PVC membrane with an alcoholic solution.