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If the probe is in a concentrated KCl storage solution, then that should be fine, even if the pH is a bit off. Does that answer your question?

Hi there. Pure KCl should be neutral, right around 7 pH. One explanation for the pH you are seeing is the solution may be made using low pH water, or there may be bacterial growth bringing the pH down.

They can be left out for an hour or so without any problem. Past that time, the glass and junction may dry out, resulting in delayed response time until water rehydrates those parts. The actual effects of leaving an electrode out vary greatly between designs and different models, so results may vary.

@@phionicsinc.4832 sweet thank you for your reply copped a bluelab and want it to last

If you are sure that only DI water and KCl was added to the solution then do not worry about it. The concentration of the salt is much more important than the pH of the solution.

@@phionicsinc.4832 thankyou sir for your reply.

Good day. I just got 2 ph metres via AliExpress. One for water and one for food. First day using it to check the ph of water, they both have the same reading. Fast Forward to the next day and the values are different. Now I don’t have access to getting potassium chloride to make storage solution but please Is it possible to use RO water or distilled water with salt to create the storage solution?

@@odogwuhenry Yes, any salt is better than no salt when preserving the electrodes.

@@phionicsinc.4832 I appreciate this. I will return to give results after I have applied this knowledge.

Thank you very much. We're glad you like it!

The role of KCl is explained more in this video: ua-cam.com/video/z0-8T9Igj6U/v-deo.html If you still have questions after watching it then please don't hesitate to ask!

Thank you very much for the correction! Hopefully we can get that corrected shortly.

pH probe storage solution is very easy to make using KCl bought from anywhere. For a 3M solution, you need 22g per 100 mL (some of it may not dissolved and that's fine). You don't even need pH 4 buffer solution to mix it in. Very little grows in KCl solution so it should be fine to store for 2-3 months or longer. Just replace it if you start to see mold or bacterial growth.

@@phionicsinc.4832 100ml of which liquid? If water, wouldn't de-ionized be better? That sounds like a lot of kcl per 100ml? Can I reference you to this vid- ua-cam.com/video/UrasQN9tBqs/v-deo.html

I have this same question ⁉️ and also have seen the same video and comments about using a ph4 buffer

@@arahant69 100 mL of deionized water is best but tap water is fine as well. The amount of KCl we recommended is a lot (3M) but that is because you want a fully saturated solution. Some of the KCl will not dissolve completely. The 1g recommended in the video amounts to approximately 0.13M KCl solution which is not sufficient to prevent reference dilution so will reduce the life of your electrode if stored for months or years in that solution.

@@ElFresco214 The video likely recommended it because the probes they manufacture use a reference solution with 4 pH buffer. Ours and most other manufacturers use a saturated KCl solution instead which is why that is recommended for storage. www.coleparmer.com/tech-article/ph-electrode-care www.westlab.com/blog/2017/11/29/what-is-the-correct-way-to-store-a-ph-electrode These actually recommend 4M KCl but we find that 3M KCl works for our electrodes.

Hi Tim! It's perfectly fine if the salt doesn't dissolve completely. This means the solution is saturated and should match the reference solution inside the electrode. Perfect for storage!

Thanks for your response regarding dissolving potassium chloride Tim Davy

As long as nothing else is added to the muriate of potash, then it should work for storing a pH probe in.

Any amount of time the sensor is left out of water allows evaporation through the junction. It also dries out the bulb and may require soaking the electrode for a while to rehydrate it. Any amount of time that the electrode is left dry or in water will reduce the lifespan. The electrode could be left in normal water for a few days, weeks, or even a month and still work, but the electrode will be diluted slightly and not work for as long after that. In contrast, KCl storage solution preserves the electrode perfectly.

@@phionicsinc.4832 thank you.

That's an interesting idea! Storing a probe with humidity and pressure may work. It seems far easier to store in KCl, if available.

Most electrodes use a KCl solution for their reference but check with your manufacturer to confirm. If it does use KCl, then you can simply mix your KCl salt in RO/DI water to make a 3.0M KCl solution that preserves the electrode. You do not need to mix it with a 7 pH buffer.

pHionics Inc. thanks a lot

Haha that is correct. We appreciate your support!