ethidium bromide vapour?

Tom Knight tk at
Sat Sep 10 17:24:25 EST 2005

"jg374 at" <jg374 at> writes:

> A couple of people in our lab add ethidium bromide solution to hot
> agarose (i.e. nearly boiling), and claim that ethidium bromide cannot
> escape as a gas so there is no danger. This runs contrary to
> everything else I have heard, which says the agarose solution should
> be left to cool first, or the etbr added in a fume cupboard. Obviously
> this later method seems to be the safest, but is there any merit to
> their claim?

Ethidium bromide has completely negligible vapor pressure at 100C.  I
*suppose* you might be concerned about it splashing.  But why are you
so concerned about below-detectable-limit EtBr when there are *much*
more hazardous things in your laboratory, such as chloroform,
formaldehyde, or phenol?  My theory is that people worry because they
can see high concentrations of it.

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