FW: Purification of Genomic DNA

Sergio yokese at hotmail.com
Tue Nov 9 13:24:40 EST 2004

Deanne Bell wrote:

> Regarding A260 / A280 for DNA quantification - this is from my personal
> experience thus it is only my opinion - there are lots of substances
> carried over from a DNA prep that contribute to false A260 readings.
> I prefer to run 2 - 3 ul of my DNA prep on a 0.8% agarose gel, along
> with a set of standards for molecular mass (my set is from biorad and
> has a 1000bp fragment with 100ng of DNA; a 700bp fragment with 70ng DNA;
> a 500bp fragment with 50ng of DNA and a 200bp fragment with 20ng DNA).
> Stain the gel with ethidium bromide.  I use our imaging system to do
> spot densitometry in order to QUANTIFY my DNA - the brighter the band,
> the more DNA.  The gel also allows me to see the QUALITY of the DNA. 

I agree... A260/A280 tells almost nothing about the prep. An agarose gel 
is the way to go.


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