Eppendorf BioSpectrometer basic - Manual (Page 75)

75
Troubleshooting
Eppendorf BioSpectrometer ® basic
English (EN)
9 Troubleshooting
9.1 General errors
Error Possible cause Remedy
Measuring results
are imprecise. • Reagent is past its shelf life.  Ensure that the reagent is still within its shelf life
and properly prepared.
• Reagent has not been
prepared properly.
 Use clean demineralized water of adequate quality
for preparation if required.
• Pipetting is not correct.  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.
• The cuvette is
contaminated.
 Clean and rinse the cuvette. When replacing a
cuvette, pay attention that the optical window of
the cuvette remains clean and that you do not
touch it with your fingers.
 If the cuvette window has become soiled from
fingerprints, wipe it clean using a lint-free lab
cloth soaked in ethanol or isopropanol.
• The cuvette is not filled
completely with measuring
solution, and it contains
bubbles.
 Ensure that the required minimum volume of the
cuvette for a measurement is reached and that no
bubbles are in the measuring solution.
• Turbidity of the measuring
solution.
 Centrifuge the turbid measuring solutions
containing particles and use the clear supernatant.
• Spectrophotometer is
drifting.
 Contact Eppendorf Service.
 Observe the ambient conditions.
 Prevent temperature changes.
• Cuvette shaft is dirty.  Clean the cuvette shaft.
The measuring
results are not
correct. • The method has not been
programmed correctly.
 Ensure that the method parameters are entered
correctly.
• The standard solution has
not been prepared correctly.
 Ensure that the correct standard is used and that
the measuring solution for the standard is
prepared correctly.
• The absorbance of the
reagent is drifting.
 For instable reagent absorbance and end point
methods: When measuring a long series of
samples, measure the reagent blank value not only
at the beginning but also during the sample series.
If the reagent blank value drifts strongly, the
reagent is not appropriate for error-free
measurements and has to be replaced by a new
reagent.
• The cuvette is not
positioned correctly.
 Position the cuvette in the cuvette shaft so that the
optical window points towards the direction of the
light path.
 Photometry light path: from back to front