Table 1 Interferences
Interference Selectivity coefficient
Potassium (K
+
) 0.1 (interferes more)
Sodium (Na
+
) 0.002
Magnesium (Mg
2+
) 0.00002
Lithium (Li
+
) 0.00003
Calcium (Ca
2+
) 0.00006 (interferes less)
Section 7 Verify the calibration
Measure the value of a fresh standard solution at regular intervals to make sure the result is
accurate. The meter compares the expected standard solution value to the measured value and
accepts or rejects the measurement. The user can change the standard solution and acceptance
criteria for verification in the probe-specific settings.
Note: Password protection may prevent access to the acceptance criteria.
7.1 Verification procedure
1. Go to the
verification menu.
The display shows
the standard solution
to use for
verification.
Note: Menu name for
HQd meters: Run check
standard.
2. Pour 25 mL of the
standard solution
into a 50‑mL beaker.
3. Add one
Ammonium Ionic
Strength Adjustor
(ISA) Solution Pillow.
4. Add a stir bar.
Put the beaker on an
electromagnetic
stirrer. Stir at a
moderate rate.
5. Rinse the probe
with deionized water.
Dry the probe with a
lint-free cloth.
6. Put the probe in
the standard solution
with the sensor fully
in the solution. Do
not put the probe on
the bottom or sides
of the beaker.
7. Shake the probe
from side to side to
remove air bubbles.
8. Stir for 30 to
60 seconds, then
read the value of the
standard solution.
The meter accepts
or rejects the result.
English 9
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