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.
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.
Make sure that you have the right electrode for your application. Specialty electrodes will last longer if you are measuring substances other than water. See 4 Essential Tips for Choosing the right pH Meter / Electrode
How to use the Selectech pH Maintenance & Calibration Kit:
- 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.
- Place the electrode tip in the pH7 solution and press calibrate on your machine. Once calibration has been accepted …
- Rinse the electrode in deionised water, blot dry*, and then place in the pH4 solution and calibrate.
- Rinse and dry again and place in the pH10 solution to calibrate for pH10.
- If the readings fluctuate, the reason could be twofold: faulty standards / buffers or a faulty electrode.
- 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
- 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.
Updated July 2019.
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