pH Electrode

Care and Storage of a pH Electrode
pH electrodes do not last forever!

The life of your pH electrode is not infinite. A number of factors affect the life span of your pH electrode. The higher the temperature that the electrode is used at, the more extreme the pH, how often the bulb dries out and needs to be rehydrated, how roughly it is used; all these factors and more shorten the life span of your electrode. An electrode that is well maintained and cared for can last up to 2 years, one that is not well maintained will not last as long, and one that is well maintained will not last significantly longer.

Quick links:
Placement
pH elctrode and algea
Why you need to calibrate
pH Electrode replacement
Never store an electrode dry
Regeneration of pH glass electrodes
Buy a new elctrode



Placement
  • The pH electrode should be placed 1/3 to 1/2 of its length into the water (see picture below)
  • Place the pH electrode where the water circulation is good.
  • Do not place the pH electrode directly above the CO2 diffuser.


    • Placement of the pH electrode


    pH elctrode and algea
     The probe should be cleaned and recalibrated periodically. Use a paint brush (soft brush) to gently clean the delicate probe tip at each water change.
    A soft toothbrush works also very well.
    Don't ever let the probe tip dry out! This is most likely to happen during water changes.

    Use a soft brush to clean the tip
    Do NOT use sharp tools, abrasive materials, or cleaning powder.


    Why you need to calibrate
     The characteristic of a pH electrode will change with time due to electrode coating, contamination and aging.
    And even a pH electrode would be stable over time, pH electrodes cannot be produced with identical characteristics.

    In practice the response of a real pH sensor does not exactly follow the Nernst equation.
    This difference between the theoretical and actual behavior of a pH electrode must be compensated for.
    A calibration is required to match the pH meter to the current characteristics of the used pH sensor.

  • Click here for calibration Guide


    • pH Electrode replacement
     The pH electrode below has been used for long time and the contamination will result in a sluggish or non-responsive electrode because your electrode doesn't deliver the right electrical potential.

    There is algea penetrating the electrode (dark area) and KCl crystals (white) inside the electrode.
    It is about time to replace the unit with a new fresh electrode.




    Never store an electrode dry
     pH glass electrodes need to be kept moist at all times.
    If an electrode dries out during storage, a regeneration procedure is required to restore the hydrated glass layer
    and the reference junction in order to make the electrode operable.

    The pH electrode bulb needs to be moist at all times. When you are done with the electrode pour electrode storage solution into the cap that came with the electrode and put the cap over the bulb of the electrode. Keep the cap on until next use. If the electrode is being stored for a long time you may want to check the cap to be sure the storage solution is still in the cap and keeping the bulb moist.
    DO NOT STORE THE pH ELECTRODE IN DISTILLED WATER.
    Storing the pH electrode in distilled water will shorten the life of your pH electrode. If you do not have electrode storage solution use pH 4 buffer solution. If you have neither electrode storage solution or pH 4 buffer solution you can use pH 7 buffer solution for a short time.


    Regeneration of pH glass electrodes

    The pH glass membrane, the probe tip, is the sensitive part of your electrode. If the glass membrane dries out during storage and sometimes after a rough cleaning procedure gets damaged, you need to restore the hydrated glass layer.

    Below are suggestions for three different regeneration methods you can use. The first method is the easiest to handle and the third method is the most powerful.

    What method you choose to use will depend on your experience and knowledge about the pH electrodes you are using. If it's the first time you regenerate your pH glass electrode, start with the first method. If this not helps and the electrode behaves in an inappropriate way, as a slow and sluggish response, take the next step and try method 2. You still have a problem with the pH electrode? Okay, it's time to try the "final step", method 3.

    Regeneration method 1

    • Soak the pH electrode in reference electrolyte solution for a couple of hours (overnight).

    Regeneration method 2

    • Soak the pH electrode overnight in 0.1 M HCl.
    • Rinse the electrode carefully in water.
    • Soak the electrode in buffer 4 for about one hour.
    • Rinse.

    Regeneration method 3

    Manufacturers of pH electrodes usually sell their special solution for regeneration of glass electrodes. An example of a regeneration solution is a mixture of hydrochloric acid (HCl) and hydrofluoric acid (HF). For the appropriate procedure, see the instruction manual for the regeneration solution.

    However, general guidelines for using a reactivation solution are:

    • Immerse only the tip of the electrode, the pH sensitive glass membrane, in a sample of regeneration solution for 5 to 15 minutes. It is important to avoid any contact with the electrode body and the regeneration solution. The electrode body can be damaged by the aggressive solution.

    • Rinse carefully and thoroughly with water for 1-3 minutes.

    • Soak the pH electrode in buffer 7 for about one hour.

    • Allow the electrode to stand in reference electrolyte solution, overnight (see method 1).

    Be careful when handling a reactivation solution. It is very toxic and aggressive to clothing, skin, and especially eyes.

    Ready to be used

    If your regeneration procedure has been successful, your electrode is now ready for calibration and measurement.




    Buy a new elctrode
     We offer new pH electrode in our shop and you can also find calibration solutions there.

    You can always contact us if you need help with your pH electrode and calibration.

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