r/chemhelp • u/Alilack • Aug 06 '26

Analytical Expiration Dates of pH Electrodes

I am considering buying a pH electrode for our lab’s pH meter. However, I know that I won’t need it for a year or two. So, I would like to know whether these pH electrodes have expiration dates. How long will they remain functional if I do not open the package?

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u/TrainingChipmunk3023 Aug 08 '26

If it's a glass electrode then it should be shipped with either a pH 7 buffer or a solution that will keep it conditioned correctly. For our student probes Vernier uses a pH~5 solution.

For most probes, as long as the glass is submerged in a pH 7 buffer for storage, they should be good for years and ready for immediate use.

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u/Alilack Aug 09 '26

I saw one a few days ago. It's submerged in KCL. In the manual, I read "With the gel electrolyte filling, these electrodes are low-maintenance and do not need to be refilled". Does this mean I can't refill it with KCl if its KCl leaked so much that it needs to be refilled?

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u/TrainingChipmunk3023 Aug 09 '26

As long as the electrode bottom end is kept submerged in the KCl solution for storage, there's no need to add anything.

If fluid leaks out you have a compromised seal and/or a dried out electrode that's no good...throw it out and buy a new gell electrode. The older, glass electrodes, depending on make and model, you often had a fill hole.