ethidium bromide vapour?

Austin P So (Hae Jin) nobody at
Sat Sep 10 21:42:18 EST 2005

EtBr will not "vapourize".

If you add it to hot agarose, you will degrade it (lower sensitivity). 
But of course you are adding a lot anyway, so it won't really affect 
your results too boils down to a time and convenience issue.

Speaking of which...I'm very impatient. So I usually cool hot agarose in 
a cold water bath with constant stirring (usually about a minute). And 
then when it has cooled enough to place on your cheek without "hurting", 
then I pour. If I'm really pressed, and if I can find the space, I put 
the gel into a fridge or freezer until it has solidified.

You add it in a fumehood or a designated area to limit exposure. 
Sometimes, powder can line the bottle cap of a solution too, so you 
might cause contamination this way.

The other thing to keep in mind is that any intercalators like EtBr will 
  affect the eletrophoretic properties of DNA when it is included in the 
running buffer or the gel. So it is important to think about your 
application to determine how best to stain.


jg374 at wrote:
> 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?

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