Horiba Scientific LAQUAact D-72G, Instruction Manual

Page: 45 / 94

pH measurement
25
●
Performing measurement
You can perform measurement in the measurement mode by immersing the pH
electrode in the sample. Also, you can use the automatic hold function to perform
stability judgment of the measured value.
1. Wash the pH electrode with pure water (or
deionized water) and wipe it with filter paper or
tissue paper.
2. Open the internal solution filler port of the pH
electrode.
If calibration is performed with the port closed, the
internal solution does not flow and the
measurement value is not stabilized. Make sure to
keep the port open during calibration.
3. Immerse at least 3 cm from the tip of the pH
electrode in the sample solution.
In order to flow the internal solution into the
sample solution, immerse the liquid junction in the
sample solution surely.
4. While the pH electrode is immersed in the sample solution, press the key.
Stabilization judgment starts and the HOLD icon blinks. When the value is stabilized,
the HOLD icon changes from the blinking state to the lit state and the display is fixed
to the measured value at the stable time. Press the
key again to release fixing the
measured value.
Note
The criteria of stability judgment in the automatic hold measurement are as follows.
Potential variation for 10 seconds is less than 1 mV (0.015 pH equivalent) and
temperature variation is less than 2.0°C
key
Stabilized