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NanoPlus Operator’s Manual Calibrating the pH Electrode
Mar 2014 A-19
Calibrating the pH Electrode
Calibration is not required for each measurement, but it should be done once a day, for example,
before the first titration. Use commercial pH standard solutions to calibrate the pH electrode. Two
or three kinds of pH standard solutions are used for pH calibration (2-point or 3-point calibration).
Standard solution of pH6.86 (phosphate) is necessary for both 2- and 3-point calibration.
1. Open the rubber stopper on the electrode before starting calibration. The rubber stopper
should always be open during measurement or calibration and closed when not in use.
2. Select the pH Calibration icon in the pH Maintenance function panel; the pH Calibration
dialog is displayed.
3. Use the drop-down menu at the Calibration Points field to select the number of points (2 or
3 points).
4. Click Buffer 1 and select the standard solution of pH6.86 (phosphate) from the drop-down
menu. Click Start .
A progress bar at the bottom of the screen displays during standard solution measurement.
Measurement ends automatically when the potential becomes stable.
5. Click Buffer 2 and select pH4 standard (phthalate) from the drop-down menu. Click Start .
6. Click Buffer 3 and select pH9 standard (borate) from the drop-down menu. Click Start .