horiba LAQUAact-PD110, Инструкция по эксплуатации, Страница: 41 / 117

pH measurement
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Performing calibration
Calibration is necessary to measure pH accurately.
We recommend performing calibration once a day, before the first measurement.
According to the following procedure, perform calibration accurately.
Note
・
Perform two-point calibration using pH 7 and pH 4 when you know that the sample is
acidic; pH 7 and pH 9 when you know that the sample is alkaline.
・
Perform three-point calibration using pH 4, pH 7, and pH 9 when the sample is unknown.
・
You can confirm the current calibration data in the data mode and delete the calibration
data in the setting mode. (Refer to "Displaying the latest calibration and inspection data"
(page 56), "Deleting calibration data" (page 60).)
• pH standard solution setting is USA or NIST
This section describes the procedure for two-point calibration of USA, pH 4 and 7, as a
general calibration example.
1. Clean 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 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.
Stability judgment automatically starts and the pH icon blinks until the measured
value stabilizes. When the measured value stabilizes, the pH icon changes from the
blinking state to the lit state.
Tip
The standard solution type for the calibration is shown on the upper right screen.