HACH LANGE QuikChem 8500 2 Series, Maintenance And Troubleshooting Manual, Page: 16 / 78

Problem Possible cause Solution
The baseline is not at
zero. For most chemistries,
the baseline will not
be at zero.
• Examine the baseline in the Lachat method support data. The
baseline should be less than one volt of the support data in
the method. If the baseline increases and/or if the blank
peaks are negative, the carrier is probably contaminated.
• Remove the filter and flow cell while the baseline is shown. If
the baseline changes significantly when either component is
removed, the issue can be the component or the installation
of the component.
The probe continues
to hit the cups. Wrong sample rack
• Make sure that the correct type of rack is selected in the
software.
• Make sure that the rack is attached correctly to the sampler
• Make sure that the probe is not bent.
• Make sure that the probe is aligned correctly with the wash
bath.
Sample racks are not
installed correctly.
Probe might be bent.
Peaks are smaller
than the ones
received in the past. Bad reagent
• Make sure that the standard preparation, reagent preparation
and shelf life are correct.
• Make sure that the sample loop and the correct interference
filter are located in the correct location.
• Make sure that the transmission tubes are in the correct
containers.
• Make sure that the time for sample to valve is good.
Sample loop is not
correct
Reagent order is not
correct
Timing is not correct
Interference filter is
not correct
The ammonia peaks
are very small. The pH of the
chemistry is not
correct
• Make sure that the pH at the waste line is 13.
• Do the QuikChem method for preparation. Make a fresh
solution.
• Make sure that the heater is set at 60 °C (140 °F) or other
temperature given in the QuikChem method.
The hypochlorite is
expired or not made
correctly
The heater is not set
to the correct
temperature
Stains in the tubing
(after the heater)
when ammonia is
used The pH is not correct
• Make sure that there is pH at the exit of the flow cell.
• Use a reagent-grade 4–6% hypochloride solution.
Caused by the use of
household bleach
The QuikChem
method shows
support data that
cannot be made on
the system. Standard and/or
reagent preparation is
not correct
• Make sure that the formulas in the QuikChem method are
done correctly and that the standards have been prepared
correctly.
• Make sure that the manifold, the interference filter wavelength
and the sample loop are correct.
• Look for flow problems.
Manifold configuration
is not correct
Interference filter
and/or sample loop is
not correct
Flow problems
Flow cell leaks at
fittings or around
glass Worn out O-rings and
flares
• Change the flow cell flares and O-rings. Use the pump to
move water through the flow cell to make sure that the leak
has stopped.
• Clean the leaked fluids off the detector and the fiber optic
cables.
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