What to do when you receive a pH zeropoint error message.
Typical Result:
- Most Common- Zeropoint after calibration did not fit your calibration settings. This might simply be because the settings did not correspond to the used pH buffers or the sensor that you used
- Common- Sensor needs to be cleaned and re-calibrated see How to Clean and Calibrate your Zirkon® pH Sensor
- Least Common- Sensor is old, replace sensor
pH zeropoint error
Cause: After calibration, the zeropoint was not within -60…60mV
Suggested remedies:
- Check settings buffer/internal buffer; clean sensor and repeat calibration.
Note: The internal buffer is the buffer filled into the pH-glass bulb. The pH of this buffer represents the zeropoint of your sensor. You can find the pH of the internal buffer printed on the sensor, whenever it is not pH 7.
- Change reference electrode/change sensor
A zeropoint offset can be caused by a worn-out or coated pH-membrane. Check the glass bulb and the reference, especially the junction and the reference element, for damages or discoloration. Even without visible damages or discoloration, the pH-membrane can be contaminated (e.g. grease). Clean the sensor and re-calibrate it afterwards.
Note: If the instrument issues a calibration error (zeropoint or slope), check the INFO menu in the calibration menu. It lists the results of the last calibrations with date and time and helps determine whether the current results are following a general trend or if the current results differ greatly from previous results, making a damage or some calibration error more likely.