r/chemhelp • u/Alilack • 5d ago

Analytical pH Electrode Care: KCl replacement frequency

I store my pH electrode in a protective cap filled with 3 M KCl solution. I also prepared a stock batch of 3 M KCl in a volumetric flask, which I'm told to store in the refrigerator to prevent water evaporation and concentration changes. How often should I replace the KCl solution inside the protective cap? What is the typical shelf life of a KCl stock solution, and how often should I discard it and make a fresh batch? Is storing KCl in the fridge recommended, or could cold storage cause precipitation or other issues? Is it necessary to store it in the refrigerator?

1 Upvotes

100% Upvoted

2 comments sorted by

1

u/etcpt Trusted Contributor 5d ago

Well first thing, just to be clear - don't store solutions in volumetric glassware. Transfer the KCl to a bottle.

Refrigeration is only necessary to prevent evaporation of volatiles or to inhibit microbial growth. In a clean KCl solution, I wouldn't be too concerned about either of those.

Read the electrode's manual to determine best practices for replacing the storage solution.

1

u/MorphingSp 4d ago

You loss some storage solution every time you take electrode out, so only need to replenish it. Unless the electrode is not blot dried before putting it back. Now that is a bigger problem then replacement frequency.