Detection limits of 32P ?

Bernard Heymann bheymann at
Thu Apr 15 16:50:48 EST 1993

In article <11857.jdboer at>, jdboer at SOL.UVIC.CA ("Johan de Boer")
> We have some dispute about how much 32P end-labelled DNA fragment can be
> detected by autoradiography. I am sure there is someone who has a pretty
> good idea. Any takers?
> Johan de Boer


The detection limits of autoradiography depends on how long you expose
the film to the gel. I know of instances where people have developed their
autoradiograms for months, although that is hardly practical. The second
variable is of course the specific activity of the 32P used.

The easiest way to find out what the limit is for your protocol with
32P of a specific activity is to compare your autoradiogram with
scintillation counting of the same sample. You can then calculate how
much labeled DNA would give you a detectable band within a reasonable time.

I hope this info is of use :)

Bernard Heymann
bheymann at

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