Eppendorf BioPhotometer plus - Manual (Page 19)

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5 Operation
BioPhotometer plus — Operating manual
5.3.4 Finalize the method
1. Press one of the method group keys to return to the method selection and open the next
method, if necessary.
2. After all measurements are complete switch off the device.
3. Slide the cuvette shaft cover forward to protect the shaft against contamination.
5.4 Nucleic acids
The methods provided in the method groups "DNA" and "RNA" differ mainly in the
preprogrammed factor.
Additionally, for the methods "OLIGO DNA" and "OLIGO RNA" the selection of the parameter
"MOL. UNIT" (molar concentration unit) differs from that of other nucleic acid methods. This
parameter is only required for special conversions described at the end of this section.
As optical path length of the cuvette the value "10 mm" has been preprogrammed. If you modify
the value the modified optical path length is taken into account by the device when calculating the
results. Therefore you do not need to change the factor for the evaluation.
Results display
In addition to the concentration result and the absorbance at measuring wavelength 260 nm the
absorbances at 3 additional wavelengths and the quotients 260/280 and 260/230 are displayed
as an indication for the purity of the measured nucleic acid sample. The absorbance at 340 nm
should be near zero for pure samples.
Turbid measuring solutions have raised absorbances at all measuring wavelengths distorting the
measuring result. You can partially correct this by enabling the parameter "CORRECTION A
340
".
The absorbance value for 340 nm is then highlighted in the display with the cursor to indicate that
the correction is enabled.
The last measured concentration result can be converted into molar concentrations and/ or
nucleic acid amounts (mass unit or molar unit) if desired:
Top: method name and sample number
Center: result and unit
Bottom left: absorbance quotient ("ratios")
Bottom right: absorbance results
Top: input of the total amount of the sample
Bottom: input of the base pairs (for single strand
nucleic acid: the bases) or molar mass. One of the
two entries suffices.
All entries must be confirmed using the Enter key.
Display of the calculated results for the molar
concentration and the sample amounts in the total
amount.
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