Ionode IJ pH V5.1 - Manual (Page 18)

Ionode IJ Instruction Manual 18
4.3. Measurement
1) Turn on the pH meter and connect the pH
electrode. Connect a temperature sensor
(ATC) if appropriate.
2) Remove the electrode from its wetting cap
or storage solution and rinse with distilled
water.
3) The electrode must be initially calibrated for
offset and then for slope.
4) For offset calibration, immerse the electrode
in a first buffer (pH 7.0 or 6.88) and stir until
the reading is constant. Stop the stirring
and take the reading when stable. For
meters without automatic buffer recognition,
adjust the offset control to the first buffer.
5) Rinse the electrode and repeat the process
for a second buffer. The second buffer
should bracket the expected pH of the
sample and ideally be at least 3 pH units
apart from the first. Do not use this buffer
for the primary calibration (see Step 4
above). For meters without automatic buffer
recognition, adjust the slope control to the
second buffer value.
6) Rinse again and check in the first buffer.
For a new electrode, the reading should be
within ±0.02 pH of the buffer value.
Otherwise, repeat the calibration. Check the
slope (see
Slope ). If necessary, clean the
electrode with Jif and re-check.
7) Rinse the pH electrode with deionised water
or portions of the sample to be measured.
8) Immerse the pH electrode in the sample.
Stop stirring and take the reading when
stable.
9) Periodically check the offset and slope (see
Offset and Slope )