On Mon, 14 Oct 1996, Mike wrote:
>> Does anyone know whether traces of phenolics in DNA can lead to an
> overestimate of DNA conc. using absorbance at 260nm? Most of my
> extractions have a 260/280 of 1.8-2.0, but occasionally a 3-3.6 appears
> that leads me to suspect phenolics bound to the DNA may be producing
> screwy results. I would expect my DNA to be too fragmented to allow for
> easy determination of concentration on an EtBr gel (the extent of
> shearing isn't really important for what I want the DNA for).
> Any advice or ideas would be greatly appreciated.
Yes, phenol will interfere with OD of DNA solution.
Instead of running agarose gel, you could spot your DNA (1 microlitre) on
agarose/Ethidium bromide (in a petri dish), to be compared with spots of
known concentrations (dilutions of DNA MW markers, for example). This will
give you a pretty good idea of th eamount of DNA in your prep.
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