Wed Jan 18 13:25:27 EST 1995

Everyone using S35 labelled nucleotides needs to understand the
following safety issue. When they irradiate to create the S35 labelled
target molecule, they also make other S35 labelled species, some of
which are volatile acids. When you open the vial, a cloud of S35
labelled vapor comes out and will be trapped on basic or buffered
surfaces (like inside your lungs).  The same thing happens when you
heat a solution containing the S35 labelled nucleotides.  If you don't
believe it, put an open container of S35 in a closed space with a
scintillation vial containing some basic substance to act as a trap;
then count it.  

You need to handle this stuff in a chemical hood, especially when you
open the stock vial or heat reactions in open tubes.  When you have
tubes with S35 out of the hood, keep them sealed or on ice as much as
possible.  You can do PCR safely with it; just avoid the variety that
makes you open the heated tubes.  Also keep in mind that if you put
open tubes in an incubator, you're going to get a labelled condensate
on the cooler surfaces of the incubator (usually the door).  Then it
gets all over your gloves, etc without you seeing it.  Then it gets
spread everywhere and all your students say "It's not us, it's some
phantom that sneaks into the lab in the middle of the night and tracks
S35 around."

Steve Hardies, Assoc. Prof. of Biochem., Univ. of Texas HSC at San
Hardies at uthscsa.edu

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