Radiometer Analytical MeterLab PHM220 Mode D'emploi page 14

Preparations before a Calibration
1. Prepare the electrodes as described in the appropriate operating in-
structions.
2. Mount the electrodes on the electrode stand and connect them to the
proper terminals on the rear panel of the PHM220. Proper stirring
should be applied during both calibration and sample measurements.
The SAM7 Sample Stand, which is a combined electrode holder and
magnetic stirrer, is recommended.
3. Pour the desired buffer solution into a beaker. Select the buffer close
to the pH value of the samples. To obtain the highest accuracy, the pH
values of the buffers used during a two or three-point calibration should
lie on either side of the pH value of the samples.
4. Apply stirring and immerse the electrodes in the buffer solution. Make
sure that the electrodes do not come into contact with the bottom of
the beaker or the stirring device. With the SAM7 Sample Stand, use of
the stop rings will conveniently secure the electrodes at an appropriate
height. If no magnetic stirrer is used, stir the solution by gently shaking
the beaker.
5. Press the Mode key and select "pH" with the left or right arrow key.
Note: You can edit a calibration to fit your specific tasks, details on how to edit
a calibration start on page 33. When you have finished editing, start the
calibration procedure by pressing the Cal key.
A step-by-step description of the two calibration procedures available with
the PHM220 follows, AUTO on page 15 and FIXED on page 18.
14
Chapter 2
Calibration Procedures