An ion-selective electrode provides the fastest and most reliable way to monitor and control your pH. However, the measuring technique used for this pH electrode shortens its life, forcing you to replace it frequently.

The article here discusses about why does it happen and what can be done to improve the replacement interval?

 To know more about pH, you can read the Visaya Definitive Guide on pH measurement and pH meters here

1 – Selection

This point, above all others, can ensure the long and happy life of your pH electrode before it goes to the other side. Choosing the right model requires process data such as measurement range, temperature, and medium composition. Even intermittent stress factors, like chemical cleaning and sterilization, may factor into your choice of  membrane and diaphragm.

pH Electrode

Picking the wrong electrode can result in diaphragm clogs, membrane degradation, medium instability, and more.

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CM442

2 – Regeneration

Can you extend the life of a pH electrode already in use? Yes! Consider this question: Why does a drop of ink in water spread itself completely through the water?

Ink diffusion pH electrode
Courtesy of Flow Illustrator

We call this phenomenon diffusion. The ink molecules move from the most concentrated point, where the drop fell, to regions of lower concentration, the rest of the water, until it’s uniformly distributed.

Electrodes undergo diffusion too. Instead of ink molecules moving around, an electrode has potassium chloride moving out and contamination moving in. That also explains why some electrodes change color over time. Interesting, isn’t it?

Next, how do you regenerate your electrode? By reversing the diffusion process! Set your electrode in a solution of potassium chloride (3 moles per liter). Some of the mineral salts lost during operation will return and some of the contaminants will leave.

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3 – Rotation

Another excellent way to prolong the life of your pH electrode is a rotation policy of two or more electrodes. Put one in use and the other(s) in a regeneration solution at the lab. When the time comes to replace the spent electrode, put it into the regeneration solution and install a regenerated electrode to continue your process.

Explaining buffer solutions

Replacing pH electrodes is inevitable. However, these three tips can make the most out of our electrode friends before they conclude their mission on our planet.

When we talk about buffer solutions, we usually mean liquids which don’t vary much in pH value when you add acids or bases to them. To achieve this stability, a buffer solution itself must have a balanced mix of acid and base. You can refer to the graphic below that will show you how to produce a buffer solution

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CPS41D

Now a pH calibration buffer solution must have an accuracy of +/-0.01 at 25 degrees Celsius. Usually, buffer solutions range in pH from 1.68 to 10.1. They must also follow ISO standards and NIST traceability policy.

Last but not least, buffer solutions can have different colors to identify their pH values. Blue indicates a basic solution, red acidic, and yellow neutral.

to know more pH and buffer solutions, you can get in touch with our engineers!

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