how to quantify pcr products

Michael L. Sullivan mlsulliv at
Wed Nov 8 10:10:32 EST 2000

>Next, I have run samples on a gel and dna is there but how can I
>quantify it?  I tried comparing the bands to bands of the marker (I
>called the company and got the formula for how much dna each marker band
>has based on how much you loaded of the marker) but I am getting numbers
>that make no sense when I do this gel estimation.

I do routinely quantify DNA fragments by running on a gel along with
standards.  What works best for me is to use cut plasmid as the standard.
I usually run 10, 30 and 90 ng of the standard, and dilute what I'm trying
to quantify to be in this range.  I think it probably helps a lot to have
the "standard" similar in size to what you're trying to quantify, so that
they generate similar types of bands (i.e. tight vs. diffuse) on the gel.
In my hands, doing it this way seems to be reasonably accurate.


Michael L. Sullivan, Ph.D

U.S. Dairy Forage Research Center
1925 Linden Drive West
Madison WI, 53706

(608) 264-5144 Phone
(608) 264-5147 Fax


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