Buffering Phenol

Tue Jun 7 11:53:41 EST 1994

 We have on occaison found that it can be very difficult to buffer phenol to
pH 8.  For reasons nobody here can explain certain lots of high quality phenol
are impossible to get to pH 8 even after overnight extraction with Tris base
0.5 M unbuffered.  The phenol remains at pH 6.8.  However someone in the lab
added a few drops of 10 M NaOH and the two phases then mixed and wouldn't
seperate.  Upon addition of 50 mM Tris pH 8 the pahses seperated and the phenol
was at pH 8 (sort of...).  Repeated extraction with 50 mM then 10 mM Tris pH 8
does not change the pH of the phenol.  While I don't wish to address this
rather novel approach to buffering phenol can anyone tell me what is going on?
Why does adding NaOH cause the phases to mix ?  Is it the salt ?  Why do we
have trouble buffering the phenol in the first place if it easily buffers once
the phases mix ?  If the salt is causing the phases to mix why does the phenol
remain buffered after repeated extractions with low salt buffer ?  And
is this "solution" usable ?

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