Section 2 -
Calibration and Measurement
For accurate results, stir all buffers and samples. Always rinse electrodes and blot dry
before transferring from one solution to another to prevent contamination. Ensure that
any electrode filling holes are left uncovered during use.
Automatic Calibration & Temperature Compensation
1.
Connect the pH electrode(s) and temperature probe and switch on using the I/O Key.
2.
Select pH mode and clear any calibration data by pressing the Clear key for 5 seconds.
3.
Place the pH electrode(s) and the temperature probe in the pH 7 buffer and wait for a
stable reading. Press the BUF 1 key. The first calibration point will now be entered
automatically at the correct value for the temperature of measurement. The Cal flag will
be displayed.
4.
Rinse, blot and place the pH electrode(s) and temperature probe in the second buffer
(4 or 10). Wait for a stable reading and press BUF 2. The second calibration point will
now be entered automatically at the correct value for the temperature of measurement.
5.
Rinse, blot and place pH electrode(s) and temperature probe in the sample. Wait for a
stable reading and record pH value.
6.
Temperature or mV measurements may be made at any time by pressing the mode
key.
7.
To adjust the E° value of the electrode, place in buffer 4,7 or 10 and press the BUF 1
key.
Note:
The performance of the electrode may be monitored by pressing the SLOPE key.
The slope is displayed as a % of Nernstian. The value should lie between 85 and 110%.
Manual Calibration
If buffers other than 4,7 and 10pH are to be used, then the calibration must be performed
manually. That is the correct pH values must be entered using the ñò keys
Follow points
1
and
2
for Auto calibration above :
3.
Place the electrode(s) and temperature probe in the first buffer and wait for a stable
reading. Check the temperature of the buffer. Look up the value of the buffer for this
temperature
4.
Use the keys to adjust the displayed reading to the value displayed in
3.
(the CAL flag
will flash). Press BUF 1 (the CAL flag will stop flashing)
5.
Place the electrode(s) and temperature probe in the second buffer and wait for a stable
reading. Check the temperature of the buffer. Look up the value of the buffer for this
temperature
6.
Use the keys to adjust the displayed reading to the value displayed in
5.
(the CAL flag
will flash). Press BUF 2 (the CAL flag will stop flashing)
7.
Rinse, blot and place pH electrode(s) and temperature probe in the sample. Wait for a
stable reading and record pH value.
8.
Temperature or mV measurements may be made at any time by pressing the mode key.
9.
To adjust the E° value of the electrode, place in buffer 4,7 or 10 and press the BUF 1 key.
