Horiba Scientific LAQUAact D-75G, Instruction Manual

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pH measurement
23
• Inspecting repeatability
You can inspect repeatability using the pH 7 standard solution by pressing the key on
the screen after calibration. Measure the pH 7 standard solution by using the calibrated
electrode to display the absolute value of the difference between the measured value
and standard solution value.
In order to inspect repeatability, you need to perform calibration of the pH 7 standard
solution with either "NIST" or "USA" set as the standard solution.
1. Wash the calibrated 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 pH 7 standard solution.
In order to flow the internal solution into the
standard solution, immerse the liquid junction in
the standard solution surely.
4. While the pH electrode is immersed in the standard 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.
Note
Repeatability inspection can be performed only once for one calibration.
Stabilized
key