peak at 270nm

Ed Stephenson estephen at
Wed Aug 26 14:23:36 EST 1998

You say that there is not a peak at 260, even though you know that there
is DNA by gel. Is it possible that your spec is miscalibrated and that
the 270 peak is actually the 260nm DNA peak? Maybe the PCR problems are
not related to the purity of this DNA, but to some other problem.

Ed Stephenson

> >  oliver.kudlacek at wrote:
> >> I have a problem with an experiment as simple as a boiling prep.
> >> Scanning the DNA after the boiling prep I get a Peak at 270nm, but no
> >> at 260nm.
> >> Sambrook and Maniatis suggest a contamination with Proteins.
> >> OK; but I can't get rid of this Peak even after repeated
> >> Phenol/Chloroform extractions.
> >> There is Plasmid DNA in the prep and I can digest it well.
> >> But there a Problems whenn I try to run a PCR.
> >>
> >> What is this Peak?? Where does it come from?? What can I do to get
> >> clean DNA??
> >>
> >> Thanks in advance
> >>
> >> Oliver
> >>
> >> oliver.kudlacek at
> >>
> Michael Barnhart wrote
> >
> >We experienced a similar problem with some RNA preps.  You didn't specify if
> >you are doing phenol-chloroform extractions as part of your normal protocol.
> >We changed protocols to fix the problem, but we suspected we might have a
> >problem with our phenol.  If you have some fresh phenol you could try, I
> >would suggest that.
> >
> I am not using the phenol-chloroform extraction as part of my
> prep-protocol. So the first conatmination can not be explained by
> phenol in the preparation. But I'll try new phenol to clean the DNA.
> Thanks for your answer.
> Oliver

More information about the Methods mailing list