DNA concentration calculation from agarose gel - DNA concentration calculation (Aug/22/2005 )

hello

is it possible to calculate the concentration of DNA sample loaded into agarose gel after running the gel and veiwing the result?

is there any formula?

or is it just approximation and requires experience ??

please help

Hi,

Yes. Many companies sell DNA mass standards (usually lambda mass standards), but you can also use a DNA sample of a known concentration. Basically, you make dilutons of your unknown (10^-1, 10^-2 is usually sufficient). You then either load your commercial mass standards, or make diliutions of your solution of known concentration. Run all of these on a gel and use some type of image analysis software (usually comes with your gel documentation software, but freeware programs are available) to compare band intensities. You can derive a ratio from the known DNA sample intensities and use that to estimate your unknown DNA concentration.

For example, say you have a standard band of known concentration- say 100ng-that is 2 times as intense your unknown DNA band. This would mean that your unknown band contains 50ng.

Hope it helps!

-Hank

Hi I use NEB DNA ladder which is quantifiable. You will be given the mass of each band, for eg, 3KB=125ng if you load 0.5ug of DNA.

hi thanks for the suggestions

i mean to try with Generuler marker , since its available in my lab

thanks again

regards
laxmi

Hi,

ya, there is usually a software in your imaging machine to let you compare the concentration of your samples by comparing with the concentration of of your ladder marker.

Good luck and all the best.