[Histonet] Re: Chromium Trioxide

[Freida Carson]

Bob is correct that there is no satisfactory substitute for chromic acid in the GMS procedure.  We found that it takes 1 hour at 56-60 degrees C in 1% periodic acid to equal the usual oxidation with chromic acid, and even then you will probable get more silver staining of the connective tissue than with chromic acid.  The paper was published in the J Histotechnol, 1999; Vol 22:119.
 
If you rinse sections very well with water before the chromic acid, the chromic acid can be used for over and over.  It is alcohol remaining on the slides that causes the chromic acid to turn brown and become unusuable.
 
Hope this helps.
 
Freida Carson

--- On Wed, 7/22/09, Robert Richmond <rsrichmond <@t> gmail.com> wrote:


From: Robert Richmond <rsrichmond <@t> gmail.com>
Subject: [Histonet] Re: Chromium Trioxide
To: histonet <@t> lists.utsouthwestern.edu
Date: Wednesday, July 22, 2009, 2:02 PM


Deanne Knutson, Anatomic Pathology Supervisor, St. Alexius Medical
Center, Bismarck, North Dakota asks:

>>We use Chromium Trioxide in our GMS stain, and the cost has escalated tremendously. Does anyone use a substitute for this chemical?  I am curious what others are using for their GMS stain. We still do our stains manually at the present time.<<

There is no completely satisfactory substitute for chromium trioxide
(chromic acid) for the oxidation step for the GMS stain for fungi,
particularly if you're trying to stain Histoplasma. Many kits
substitute periodic acid, usually in inadequate amounts. Freida Carson
published a careful study of this problem several years ago and
concluded that periodic acid could be substituted, with sufficient
time and temperature. (I think I can find this reference, but it's
probably already in our archives.) Last time I looked (2006) the
Ventana method still used chromium trioxide.

Bob Richmond
Samurai Pathologist
Knoxville TN

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