Re: Activated Charcaol

The activated charcoal removed the impurities.  If I am reading this correctly,
you are filtering the paraformaldehyde again before use? You probably can go
without filtering through the charcoal a second time .   Try it, I think once is

Rande Kline
EM Science

"Charles W. Scouten, Ph.D."  on 04/26/2002 03:16:18 PM

cc:    (bcc: Rande Kline/EMI/Merck)
Subject:  Activated Charcaol

Several years ago, I was using a perfusion with sucrose (instead of
saline) first, as described by Brain Cragg, 1980, followed by standard
paraformaldehyde (cooked into formaldehyde, don't yell)/glutaraldehype
fixative.  I had a bottle of Bakers paraformaldehyde of indeterminant,
but probably ancient, age.  Everything worked.  I ran out, and switched
to a new bottle of Fishers paraformaldehyde.  Half the fixative ran
through, then the flow stopped.  Why the change?  I made the untrained
amateurs guess that an impurity in the new paraformaldehyde was causing
the problem, that activated charcoal removed impurities, and ran the
fixative through activated charcoal after preparing it and just before
use.  This let it all flow through, and got satisfactory results.

Question:  What was going on?  Did the charcoal remove impurities, or
only reduce the concentration?  Does paraformaldehyde deteriorate with
age?  Why did the flow stop?

I have a current need to know.


Charles W.  Scouten, Ph.D.
5918 Evergreen Blvd.
St. Louis, MO 63134
Ph: 314 522 0300
FAX  314 522 0277

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