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Message or symptom
Slow stabilization time
Calibration errors
Drifting/Inaccurate readings
Out of range
12
Possible cause
Tape not removed from the filling-
hole
Contaminated glass sensor
Contaminated filling solution
Filling hole closed
Poor contact between reference
junction and solution
Probe not prepared for LIS sample For the best stabilization time, soak the probe in the
Low sample temperature or
temperature difference between
samples
Air bubbles around inner
reference electrode
Calibration not done correctly
Contaminated glass sensor
Slope exceeds the criteria for % of
theoretical (as defined in the
method slope limit)
Contaminated glass bulb
CO
absorption (for low ionic
2
strength or high purity sample)
Clogged reference
Improper storage conditions/
Dehydrated glass bulb
Electromagnetic Forces (EMF)
such as voltaic cells,
thermoelectric devices, electrical
generators, resistors and
transformers
Colloidal and/or particulates in the
filling solution.
Air bubbles around inner
reference electrode
Measurement value is outside of
range
Action
Remove the tape that is over the filling hole.
Clean the probe (refer to
Clean the probe
Drain and replace the filling solution with fresh solution.
Open the filling hole while in use by removing the filling-
hole cap from the filling hole.
Shake the probe in the solution from side to side to
refresh the reference junction.
sample for 1 to 3 minutes before the initial measurement.
Check the sample temperature. The lower the
temperature or the greater the difference of temperatures
between samples, the longer the stabilization time will
be.
Gently tap the probe with hand or shake the probe
downward to remove any air bubbles.
Recalibrate using freshly prepared pH buffers.
Clean the probe (refer to
Clean the probe
1.
Widen the slope limits by changing the PHC281
calibration settings and method.
2.
Recalibrate the probe.
3.
Run a check standard to check the performance of
the probe.
Clean the probe (refer to
Clean the probe
Use the LIS chamber for LIS/high purity samples to
prevent sample contamination.
Rinse the reference junction holes with deionized water
and then gently tap the probe with hand or shake the
probe to remove any air bubbles.
Clean or condition the probe and do recalibration.The
probe may not operate correctly if the probe has been
left dry for a long time. Condition the glass sensor and
reference junctions again:
1.
Soak the probe tip in the 4.01, 7.00 and
10.01 buffers each for 5 minutes.
2.
Rinse with deionized water. Blot dry with a lint-free
cloth.
3.
Calibrate the probe.
Do not test in areas where EMF is present. For testing in
process units (spot checking), make sure that the
equipment is grounded.
Replace the filling solution, calibrate and test again.
Gently tap the probe with hand or shake the probe
downward to remove any air bubbles.
Make sure that the sample is within the range of the
probe.
on page 10).
on page 10).
on page 10).
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