Hach-Lange HQD - Sodium (Na+) Ion Selective Electrode ISENa - Manual (Page 13)

DOC272.53.80027 13
Slope out of range (refer
to
Checking electrode
response on page 14 )
pH is too low Verify the ph is > 9 after each ISA addition
Ionic strength adjustor (ISA) not
used
Add ISA to each sample and standard
Insufficient conditioning
Condition for at least 8 hours in storage solution. Refer to
Storage solution preparation on page 8 .
Damaged electrode Contact a Technical Support Representative
Incorrect standards Calibrate using freshly prepared standards
Contaminated glass sensor Clean the electrode and recalibrate.
Drifting/inaccurate
readings
Contaminated glass bulb Clean the electrode.
Clogged reference
Rinse reference junction with ISA rinse solution thoroughly
and shake the electrode downward to remove any air
bubbles.
Improper storage
conditions/dehydrated glass bulb
Clean or condition the electrode and attempt another
calibration. The electrode may not function correctly if the
electrode has been left dry for extended periods of time.
Attempt to re-condition the glass sensor and reference
junctions by allowing the electrode to soak in storage
solution (containing Sodium ISA) for at least 8 hours prior
to use.
Stabilization criteria not optimized for
the application Adjust the stabilization criteria in the measurement options
menu.
Magnetic stirrers may generate
sufficient heat to change solution
temperature.
Place a piece of insulating material between the stirrer and
beaker.
Filling-hole cap closed Open the filling-hole cap while in use
Damaged electrode Contact a Technical Support Representative
Electromagnetic Forces (EMF) such
as voltaic cells, thermoelectric
devices, electrical generators,
resistors and transformers
Avoid testing in areas where EMF is present.
Colloidal and/or particulates in the
filling solution.
Replace the filling solution, calibrate and retest.
Air bubbles around inner reference
electrode Gently tap the electrode with hand or shake the electrode
downward to remove any air bubbles.
Out of range
Measurement value is outside of
range
Verify that the sample is within the range of the electrode.
Out of limits
Check standard value is outside of
limits set in the current method
Verify that the standard is within the limits of the current
method.
Create another method that expands the acceptable limits.
Measurement value is outside of
measurement limits set in the current
method.
Verify that the sample is within the limits of the current
method.
Create a new method with an expanded range.
Temperature out of
range
Calibration temperature value is
outside of range
Verify that the sample temperature is within the range of
the electrode.
Verify that the temperature sensor is working correctly.
Measured temperature is outside the
range of the electrode.
Verify that the standard temperature is within the range of
the electrode.
Verify that the temperature sensor is working correctly.
Check standard temperature value is
outside of range Verify that the check standard temperature is within the
range of the electrode.
Troubleshooting (continued)
Message or symptom Possible cause Action