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Illustration of ph meter tips for article on ph electrode storage.
Published On: April 12th, 2022

Given pH can vary between city water treatments, growers must be able to properly read their local water’s pH so that they can start their healthy indoor gardens. While deciding on the best pH meter is the first concern, growers and scientists must consider knowing how to store pH meter electrodes for long-term use is also of high importance.

How Exactly Do pH Meters Work?

Before using lab ph meters (manual or automated) and understanding how to store pH meter electrodes, it is important to recognize the parts that makeup laboratory pH meters. Lab pH meters are typically made up of two major components: a probe and an electronic measuring display.

Within the probe are two electrodes, including the sensor, or measuring electrode, and the reference electrode. These two electrodes work in conjunction with each other like a battery. Once the probe is placed in a liquid solution, H+ ions in the solution displace metal ions on the probe, thus creating an electrochemical flow.

The pH meter senses this flow and converts it into a corresponding pH value by comparing the generated voltage from the sensor electrode with that from the reference electrode.

The reference electrode must have a high ion concentration and low electrical resistance for this set-up to work properly.

pH meters are sensitive instruments, so it is thus critical to understand cleaning procedures and how to store pH meter electrodes properly after each use.

3 Tips on How to Store a pH Meter Electrode

There are three major aspects when considering how to store pH meter electrodes:

  • The pH probe and electrodes have been properly cleaned
  • The pH probe and electrodes are stored in liquid
  • The storage liquid contains the appropriate concentration of ions

pH Meter Storage Tip 1:

pH meters must be properly cleaned based on the solutions they are measuring. Most commonly, digital pH meters for laboratory use can be cleaned by rinsing the probe with either deionized water or a pH meter cleaning solution.

However, when using the pH meter for viscous liquids or with other solutions, more specific cleaning procedures may need to be followed. For example, oils will be better removed from the probe by using mild detergents or methanol, and proteins can be removed using a 1% pepsin solution. After rinsing the pH probe, it is important to never wipe the probe, but carefully blot dry with soft tissue, such as a Kimwipe.

Not only should this be done when preparing to store the pH meter, but also after each time the pH meter measures a new liquid. By doing so, the user prevents contamination between fluids or unfacilitated growth on pH meters used in microbiology labs.

pH Meter Storage Tip 2:

Next, it is critical to remember that pH meters must remain in liquid when considering how to store pH meter electrodes. This is because the electrodes, as described above, are surrounded by a thin glass membrane.

This glass membrane is then surrounded by a gel layer, which facilitates the movement of H+ ions between the electrodes and solution of interest. This layer must not dry out. If it does, the pH meter will no longer work properly and must be replaced. While it can be possible to resuscitate the electrodes by storing the probe in a storage buffer, this is not always possible and can drastically decrease the accuracy of pH measurements.

pH Meter Storage Tip 3:

Finally, it is important to consider the ion concentration in the storage liquid when learning how to store pH meter electrodes properly. Importantly, pH meters should not be stored in de-ionized water. Given the nature of how pH electrodes work and the Law of Diffusion, ions will diffuse from the electrode into the di-water. As a result, ions will be depleted from the electrode, thus quickly reducing the lifespan of the pH meter.

Considering this, it is critical to store pH probes in solutions containing ions. While some companies offer specific pH meter storing solutions, it is also possible to store the pH probe in the 4.01 buffers, such as those commonly used for pH meter calibration. Widely used storage buffers can also be made using 1 part potassium chloride mixed with 99 parts di-water.

Learning How to Store pH Electrodes in Your Lab

Given the importance of pH to several fields of science, industry, agriculture, food science, and more, it is critical to have trustworthy pH meters with long lifespans.

Hudson’s robotics understands this and will work with you to ensure you understand applications for pH and how to store pH meter electrodes in your lab. So, reach out today to have your questions answered!