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How to Clean your pH Electrode

Written by Janice M on . Posted in Technical Tips

The pH electrode is the most sensitive part of your pH instrument and requires special care and cleaning to perform well, in the same way a car needs to be maintained to give you efficient performance and reliable service.

electrode_tip

pH electrodes are electro-chemical sensors and generate a voltage output. They are are similar to a battery and have a shelf life. Special care of the electrode with the pH Maintenance & Calibration Kit will extend the life of the electrode, however they do have a limited life. It is important to keep one or more spare electrode/s available for replacement.

How to use the Selectech pH Maintenance & Calibration Kit:

  1. Calibrate the instrument on a regular basis (weekly or monthly, depending on use). Place a small amount of each reference buffer in 3 small beakers and a small amount of the deionised water in another beaker.

  2. Place the electrode tip in the pH7 solution and press calibrate on your machine. Once calibration has been accepted …

  3. Rinse the electrode in deionised water, blot dry*, and then place in the pH4 solution and calibrate.

  4. Rinse and dry again and place in the pH10 solution to calibrate for pH10.

  5. If the readings fluctuate, the reason could be twofold: faulty standards / buffers or a faulty electrode.

  6. Store the electrode in the Electrode Storage Solution, NEVER in distilled water (this will consume ions which will result in drifting pH readings.) Distilled water is only for rinsing.
    NOTE:
    The electrode needs to be rinsed thoroughly between sample measurements and calibrations with distilled or deionised water. Blot the electrode dry to gently dislodge excess water. Use a lint-free wiping paper* as rubbing causes the electrode to be charged thermostatically

Cleaning Electrodes:

  • For general cleaning applications, swirl the electrode in a beaker containing Electrode Cleaning Solution for about 30 seconds. Rinse in tap water before use.

  • Stubborn deposits and bacteria: soak in a 1:10 solution of household bleach (such as Jik) for 10 minutes. Rinse thoroughly before use. Alternative method: Soak the electrode in a 3.8 or 4.0 molar KC1 (Potassium Chloride)* solution heated to 50ºC for 1 hour. Allow the KC1 solution to cool down to room temperature, then rinse the electrode with deionised or distilled water*. This will open and clean the reference electrode of all contaminants.

  • Oil and Grease: rinse in dishwashing liquid or methyl alcohol. Wash in water before use.

  • Protein Deposits: soak in pepsin cleaning solution* for 5 – 10 minutes. Alternatively, you can soak it in contact lens enzymatic cleaner solution overnight. The enzymes will remove proteins from glass and plastic. Rinse in water before use.

* Available from Selectech.

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