From: jack correia <jcorreia@fiona.umsmed.edu>
  To  : Mario Garcia <mario@pinar1.csic.es>
  Date: Mon, 1 Dec 1997 09:42:26 -0600

Re: chemical incompatibility

>Does anybody know whether there is any chemical incompatibility to use Epon
>centerpieces and quartz windows with sample buffer containing fluorine
>(e.g. BeF3)?

        The danger with F (NaF?) is the pK of HF is about 3.5.  This means
below pH 4.5 you will have appreciable amounts of a substance (HF) that
etches quartz. It looks like a white nail polish on the window surface.  The
damage is severe although it may be reground by Meller at some cost, but
only in groups of 5 windows.  (I think Meller still does this?)  We have
obviously made this mistake, but luckily the student that did it did so at
my advise in an attempt to drive an association reaction; "try a range of
pH's and salt, especially fluoride (kosmotrope), concentrations"!   Keep
your pH above 5 and there should be no problems.  I am not positive, but the
Epon should be inert.
---------------------------------------------
| Dr. Jack Correia                           | 
| Department of Biochemistry                 |
| University of Mississippi Medical Center   |
| 2500 North State Street                    |
| Jackson, MS 39216                          |  
| (601) 984-1522                             |
| fax (601) 984-1501                         |
| jcorreia@fiona.umsmed.edu                  |
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