5/2/2023
| Dr. Klaus Reithmayer
Special emphasis should be placed on the maintenance and care of sensitive electrodes to optimize their service life. To extend their life, and to get the best results from your pH electrodes, we recommend following our simple advice. Remember, the electrode must always be matched to the application to obtain the best possible results.
All electrodes are delivered ready for use with a watering cap filled with 3 mol/L KCl. It is imperative that this be removed before use. The electrode tip (also referred to as the glass membrane) should then be rinsed with deionized or distilled water. If necessary, careful dabbing of the remaining water drops is advisable.
“Tip: Never rub the electrode tip with a dry cloth, this will lead to an undesirable electrostatic charge on the pH electrode.”
This cleaning must always be performed after the following:
- Start-up after storage
- Between changing buffer solutions during calibration
- When changing between different samples to avoid cross-contamination.
- Before the electrode is stored
Electrodes with a liquid filling have a refill opening. This must always be open for calibration and measurement so that the electrolyte can flow into the sample without any problems. Otherwise, the stability of the measurement signal is disturbed. In the worst case, measured material can penetrate the electrode and destroy it. After measuring, it should be closed again to prevent evaporation of the liquid and to avoid deposits of KCl.
To obtain measurement signals that are as reproducible as possible, it is recommended to use the stability control programmed in the pH meters (“AutoRead”).
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If contaminants adhere to the electrode, they can be removed as follows:
- Oils, greases: It is best to use a commercially available rinsing agent solution, or diluted lye, if necessary, at room-temperature, and remove any residue completely with distilled water. If lye is used, dip briefly in diluted acid to remove all residues. Then also rinse thoroughly with distilled water.
- Lime deposits: Diluted citric or acetic acid (10%), and then rinse thoroughly.
For storage, the supplied cap is filled again with 3 mol/L KCl. If this has leaked out during field use, for example, buffer solution or normal water can also be used for a short time. In the laboratory, 3 mol/L KCl should then be refilled in any case.
If deposits of KCl form on the watering cap or on the refill opening (for liquid electrodes) during storage, they can be removed with a little lukewarm water.
Want to know more?
Take a look at our online store and find the right pH electrode or pH meter for your application. If you still have open questions, then you can always contact our Customer Service or Technical Support.
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Further questions are answered by our expert in the blog article FAQ pH measurement.
For helpful tips within your application area, you can read our blog articles: