Buffering Phenol

Joseph C. Bagshaw jbagshaw at wpi.WPI.EDU
Thu Jun 9 10:15:27 EST 1994

1.  Consider the cost of the Tris you will use up and the amount
of phenol you will lose (some goes into every aq. phase).

2.  Consider the amount of time you will spend on this task.
Your graduate student doesn't count; she has more useful things
to do.

3.  Look up the price of buffered phenol in any of a half dozen
catalogs and compare it with the price of unbuffered phenol.

4.  Buy buffered phenol.

In article <199406071653.JAA27400 at net.bio.net> MUNGO at UVVM.UVIC.CA writes:
> 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 ?


Joe Bagshaw                        HAVE GENES, WILL TRAVEL
Department of Biology and

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