Hello,
I performed midiprep in order to purify plasmid DNA from Ecoli DH5-alpha and obtained 72ug of the plasmid DNA.
Nanodrop results showed good 260/280 ratio of 1.9, indicating a fair purity level of the extracted pDNA; however, I am concerned about the low numbers of individual 260 and 280.
260: 0.179
280: 0.091
raw 260: 0.229
raw 280: 0.14
Can anyone explain as to what these low numbers indicate, and how they affect the level of purity of the extracted pDNA?
Thank you in advance,
Manho
Double stranded DNA has an OD at 260nm of 1, if the solution contains 50 microgram/ml concentration, hence, what you may have is a good quality but low amount of DNA.
Hi there,
OD at 260nm is proportional to the sample's content in nucleotides.
@Manho Na : Well depends upon the method of extraction as well as its efficiency..you see, the absorbance at 260 nm is done by nucleotides meaning even RNA can absorb at that wavelength..hence, it can't always be true that higher OD means greater concentration. I would suggest that you carry out the gel electrophoresis and calculate the concentration by comparing with the standard ladder..That should give a closer value for your concentration..
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