pH measurement
27
Two-point calibration is complete.
When calibrating three points or more, use the same procedure to continue calibrating
the 3rd and subsequent points after the 2nd point calibration. You can calibrate up to five
points. Also, you can inspect repeatability using the pH 7 standard solution. About the
repeatability inspection procedure, refer to "Inspecting repeatability" (page 28).
Tip
The order of calibration of the standard solution is optional.
In the above example, you can calibrate pH 4 first and then pH 7.
Note
• If calibration of any standard solution is performed again, only the value of calibrated
solution is updated. If calibration is repeated, only the calibration value of used standard
solution is updated. The calibration values are retained until next calibration is performed,
the data is deleted or buffer setting is changed. For the procedure for deleting the
calibration data, refer to "Deleting calibration data" (page 61).
• It is recommended that you should clear the previous calibration data before the
calibration in order to perform more accurate calibration.
•Check of the pH electrode status
After calibration is complete, the current pH electrode status is diagnosed from the
calibration result. Refer to the following table for maintenance of the electrode.
Display
Description
Reference
Both
and ERR No.
are not displayed
Electrode sensitivity: 85% to 100%
Good condition.
－
ERR No.0004
blinks
Asymmetry potential: less than
−
45 mV or excess 45
mV Maintain or replace the electrode.
ERR No.0005
blinks
Sensitivity: less than 85% or excess 105%
Maintain or replace the electrode.
key or
key
