Eppendorf D30 BioPhotometer - Manual (Page 66)

Troubleshooting
Eppendorf BioPhotometer
® D30
English (EN)
66
The coefficient of
determination for
the regression
evaluation of the
standard series is <
0.8. • For methods with evaluation of
standard series via the regression
procedure: If the regression
evaluation for the standard series was
nonlinear, but the standard evaluation
was accepted by the user, a warning
appears after samples have been
measured.
 Use the sample results with the
reservation mentioned or repeat the
measurement of the standard series
and samples.
Scan: Some of the
measured
absorbances are
too high and are
not displayed. • For at least one scan wavelength, the
absorbance exceeded the measuring
range.
• Turbidity of the measuring solution.
• Measurements at the limits of the
photometric measuring range.
 If the non-displayed areas of the scan
are relevant: Dilute the sample or
remove the dilution via centrifugation
and repeat the measurement.
Absorbance at the
measuring
wavelength is too
high. • Turbidity of the measuring solution.
• Optical surfaces of the cuvette are
soiled.
• Cuvette has been inserted into the
cuvette shaft facing the wrong
direction.
• Too high absorbance of measuring
solution.
 Measure again considering the
possible causes.
The calculated
result is negative. • Measuring solution not prepared
correctly.
• The incorrect factor has been entered
(wrong algebraic sign).
 Measure again considering the
possible causes.
The result has more
than 6 pre-decimal
places. • Very high sample concentration.
• Concentration unit does not match
the expected range of the sample
concentrations.
 Dilute sample and measure again.
 Change the concentration unit
(Parameter Unit) and measure again.
The result is more
than 5 % outside of
the standard
concentration
range. • For methods with evaluation via
standard curves (nonlinear evaluation
method):
The sample result is more than 5 %
outside of the standard concentration
range.
 Remeasure the sample under
conditions under which the result is
within the range of the standard
concentrations (dilute sample, modify
standard concentrations and
remeasure).
• Calculation not
possible
because of
division by zero.
Absorbance
result is zero.
• Calculation
error. Division
by zero.
• The evaluation required dividing by
an absorbance result with the value of
"zero". This is not mathematically
permissible.
Examples: Calculation of a factor at
one-point calibration; calculation of a
260/280 ratio with nucleic acid
measurements.
 Check the reagents and samples used
and repeat the measurement.
Problem Cause Solution