horiba LAQUAact-PD110, Instruction Manual

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pH measurement
28
• Inspecting repeatability
You can inspect repeatability using the pH 7 standard solution by returning to the
calibration screen after calibration and ends and pressing the key. 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 "USA" or "NIST" set as the standard solution.
1. Clean 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 stable. Make sure to
keep the port open during calibration.
3. Perform the 1st point calibration. Immerse at
least 3 cm from the tip of the pH electrode in
the pH 7 standard solution.
In order for the internal solution to flow into the
standard solution, make sure to immerse the
liquid junction in the standard solution surely.
4. Press the key to enter the calibration mode.
5. Make sure that the pH icon lights while the pH electrode is immersed in the
standard solution.
Stability judgment starts and the pH icon blinks. When the value is stabilized, the pH
icon changes from the blinking state to the lit state and the display is fixed to the
measured value at the stable time.