Eppendorf BioPhotometer plus - Manual (Page 38)

8 Troubleshooting
38
BioPhotometer plus — Operating manual
8.3 General errors
Fault Possible cause Remedy
Measuring results are
imprecise. • Shelf life of reagent solution
exceeded.  Ensure that the reagent is still within its shelf life
and properly prepared.
• Reagent not prepared
correctly.  Use clean demineralized water of adequate
quality for preparation if required.
• Pipetting incorrect.  Ensure that the pipette is calibrated and that
pipetting is being performed correctly.
• Incubation procedure before
measurement is incorrect.  If the method procedure requires incubation
before the measurement, ensure that the
temperature and time for incubation are correctly
observed.
• Cuvette dirty.  Clean and rinse the cuvette. When changing
cuvette, ensure that the optical surface of the
cuvette remains clean and has not come into
contact with fingers.
 If the optical surface of the cuvette is soiled with
fingerprints, clean it by wiping with a lint-free
laboratory cloth soaked in alcohol.
• Cuvette not completely full of
measuring solution without
bubbles.  Ensure that the necessary minimum volume of
the cuvette for a measurement is reached and
there are no bubbles in the measuring solution.
• Measuring solution turbid.  Centrifuge turbid measuring solutions containing
particles and use the clear supernatant.
• Photometer drifting.  Contact Eppendorf Service.
Measuring results incorrect. • Method wrongly programmed.  Ensure that the method parameters are entered
correctly.
• Standard solution not
prepared correctly.  Ensure that the correct standard is used and that
the measuring solution for the standard is
prepared correctly.
• Reagent absorbance drifting.  (With unstable reagent absorbance and
end-point methods): when measuring a long
series of samples, do not measure the reagent
blank only at the beginning of the series, but
also during the series of samples. If the reagent
blank drifts significantly, the reagent is
unsuitable for fault-free measurements and must
be replaced with new reagent.
Other possible causes can be
found under "Measuring results
imprecise". Other possible remedies can be found under
"Measuring results imprecise".
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