Ethidium Bromide temperature - (May/11/2006 )
Hi everybody,
the boiling pt of EtBr is around 100 degree,then why should we add around 50-60 degree,please give me reply
thank you
hi
it's because there is less evaporation of the buffer at this temperature.
Btw, i boil my EtBr and nothing seems different.
it's because there is less evaporation of the buffer at this temperature.
Btw, i boil my EtBr and nothing seems different.
you should avoid to boil EtBr because it is toxic by inhalation.
that's why you should add it when the buffer is cooled to 50°C.
I put this assertion firmly in the category of random rumor. Do you have *any* evidence that ethidium bromide can be vaporized or inhaled from high temperature water? I simply don't believe it.
I don't know about EtBr evaporation, but I know is that gel boils over sometimes, and then, I'd prefer that there was no EtBr in the gel....
I heat up agarose and usually add the etbr afterward, but sometimes there's a bit leftover from the prior gel (I use the same beaker)
I keep it closed with foil and try to keep my nose out of the beaker while it's heating...I think it's mostly common sense?
I don't mess around with Ethidium. Just like your TAE buffer is steaming after you heat it, your Ethidium will probably steam up as well if it is added while still hot. Don't be dumb, add ethidium only when the temperature is below 50-55.
I would like to point out that EtBr is both an ionic compound and rather quite large molecule, MW of 394.
The vapour pressure of such a compound would be very low. And unsurprisingly the melting point of EtBr is quite hight, 260 Celsius.
The danger of EtBr vapour, is in my opinion rather low. But the danger of EtBr contamination from spitting and overboiling molten agarose is probably quite high. Thus I believe is the reason why people add EtBr once the molten agarose has cooled down.
To me it is more important to wait to the 55-60 temp to pour the gel, when the EtBr is added is irrelevant but if you pour the gel too hot you will get like swirling look on the surface of the gel instead of a nice smooth glassy surface...