LaMotte 5 Series pH Meter - Manual (Page 11)

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For a 1-point calibration, the calibration should be performed with a pH
buffer value closest to the expected sample value being measured.
The meter has automatic buffer recognition that identifi es the correct pH
buffer values during the calibration. The meter will accept calibration
values that are within ±1.0 pH units of the expected value, otherwise
the DISPLAY will fl ash “Er1” and the value will not be accepted. Press
CAL to abort the calibration and return to the measurement mode.
Always use new pH buffer solutions for calibration. Do not reuse
buffer solutions that may be contaminated and affect the calibration
and accuracy of the measurements. Promptly seal containers and store
solutions in a dark, dry, cool environment.
Before use, remove the plastic protective cap on the pH probe and
condition the glass bulb by soaking it in tap water or pH buffer
(preferably pH 4) for 1-2 hours. This will hydrate the glass bulb if the
probe is too dry or if it has not been used recently. Always rinse the
probe with clean water before and after each calibration or sample
measurement to avoid cross-contamination. For details refer to Section 5
on Probe Care and Maintenance.
3.1.1 pH Calibration Procedure
1. Pour a known pH buffer calibration standard solution, e.g. pH
7.00, into a clean, dry container. Turn on the meter and select the
pH mode by pressing the MODE key.
2. Dip the pH probe and temperature probe into the solution. Stir
gently and wait for the reading to stabilize (approximately 30
seconds depending on the probe condition).
3. Press CAL to enter the pH calibration mode. “CA” will be
displayed momentarily before the display will fl ash the current
un-calibrated reading.
4. To abort or cancel the calibration without accepting the new
value, press the CAL key. The meter will automatically revert to
the pH measurement mode.