Why does the E+H glass electrode fail to work properly after drying out?
Many customers encounter this situation on site: after the pH glass electrode is installed, due to water level drop or production stoppage, the electrode is exposed to air and dries out for a long time. When reused, the instrument reports an error or the readings are inaccurate.
The core reason is that the ion activity at the glass electrode diaphragm decreases. In a long-term dry environment, the diaphragm loses moisture, and its ion exchange capacity weakens, resulting in a significant increase in impedance. The output current becomes extremely small, and the instrument cannot detect it properly.
Key precautions for glass electrode use and calibration
To avoid dry-out failure and measurement errors, the following precautions must be taken when using glass electrodes for measurement and calibration:
- Keep it moist: When the electrode is not in use, it should be soaked in a dedicated storage solution. Never leave it dry.
- Calibrate regularly: Calibrate with standard buffer solutions regularly according to working conditions to ensure measurement accuracy.
- Avoid drying out: During production stoppage or maintenance, remove the electrode and store it properly, or ensure the liquid level covers the electrode.
- Clean the diaphragm: Clean the diaphragm regularly to prevent contaminants from blocking ion exchange.
- Check the cable: Ensure the cable is properly connected to avoid signal interference.
If the electrode has already dried out, try soaking it in storage solution for several hours to 24 hours. Some electrodes can recover their activity; if the impedance is still too high, replacement is required.
Summary
The main reasons for E+H glass electrode failure after drying out are decreased ion activity at the diaphragm and increased impedance. Proper daily maintenance and calibration can effectively extend electrode life and ensure measurement accuracy.
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