Macro 900 Operation Manual
V3
© 2013 Palintest Ltd.
www.palintest.com
Page 37 of 147
13.5.
Special Notes Concerning ISE Electrodes
The high ionic concentration of pH
calibration solutions (buffers), including
MacroCal, can cause significant offsets in
ISE electrodes.
These offsets are temporary, but best
avoided because they can cause
significant errors during both calibration
and normal operation.
For this reason all ISE electrodes are
supplied with a red rubber sealing cap.
The caps should be fitted to all ISE
Electrode during pH calibration
in
order to protect the ISE electrodes from the effects of the buffer solution.
At all other times, the ISE electrodes should be left uncovered.
13.5.1.
Calibrating the First Point (pH 7.00)
Due to the way in which pH calibration works,
the Probe must be calibrated
at pH7.00 before calibrating at pH 4.01 or pH 10.00
.
Never calibrate at
pH 4.01 or pH 10.00 before first calibrating at pH7.00.
To calibrate the pH electrode follow these steps:
1.
Fill a calibration bottle with fresh pH 7.00 solution or MacroCal, remove
the storage cap from the pH electrode, wash the Probe in distilled water,
then drop the Probe in all the way.
2. Switch the Macro 900 Meter on and wait until the temperature and pH
measurements are completely stable.
3. Ensure the temperature of the solution is between 5ºC and 40ºC (41ºF -
104ºF).
4.
Press the
MENU
key then select
Calibration.
The following screen will be
displayed.