OD 260nm to nucleic acid concentration (not primers)
This page is designed to estimate the concentration of high molecular weight RNA and single and double
standed DNA from the its OD at 260nm.
OD at 260nm
Path length (cm)
Dilution factor
Points to remember:
It is generally accepted that you also measure the OD at 280nm as well. The ratio
of OD260/OD280 should be 1.8 and 2.0 for DNA and RNA respectively. Lower ratios
suggest that the solution contains contaminating protein or phenol.
It is also possible to determine the purity of the solution with respect to salt,
organic compounds or chaotropic salts concentration by calculation the ratio of
OD260/OD230 which should be about 1.5.
The extinction coefficient of the nucleotide bases differe from each other as well
as between base paired and unpaired nucleotides. Therefore the program uses a generalised
value and assume a 'emperic' level of intramolecular base pairing in single stranded
nucleotides. This is not generally not a problem for large molecules but should not be
used short sequences that may not have equal amount of each base.
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