Re: formalin detection
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From: | "J. A. Kiernan" <jkiernan@julian.uwo.ca> |
To: | Histonet <histonet@pathology.swmed.edu> |
Reply-To: | |
Date: | Wed, 15 Sep 1999 10:36:13 -0400 (EDT) |
Content-Type: | TEXT/PLAIN; charset=US-ASCII |
On Tue, 14 Sep 1999, Skelton, Michelle wrote:
> Is there anything out there (aside from noses and eyes) to detect the
> presence of formalin in a specimen container. One of our pathologist has a
> difficult time determining whether something was submitted in formalin or
> saline.
What a lucky pathologist! The obvious reply is "your
assistant's nose." A more troublesome way is to add a
couple of drops of the questionable fluid to 2 ml of
Schiff's reagent (which you probably have on the shelf).
It will go decidedly magenta if the fluid is a fixative
that contains formaldehyde.
Do not put a drop of Schiff into an excess of the
liquid you're testing, because dilution reduces the
acidity of the reagent and changes it into something
coloured, probably basic fuchsine. The dilution colour
(a strong pink, which you see when Schiff is washed
away in tap water) is not the same as the magenta
(pink-purple) colour of the compounds formed when
Schiff reacts with an aldehyde. If you have 10 minutes
of free time, add a drop or two of Schiff to 10 ml of
saline and to 10 ml of a formaldehyde-containing
fixative, and you will see and learn what Schiff
discovered.
Of course, all this would be unnecessary if containers
were labelled properly.
John A. Kiernan,
Department of Anatomy & Cell Biology,
The University of Western Ontario,
LONDON, Canada N6A 5C1
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