Re: formalin detection

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From:"J. A. Kiernan" <>
To:Histonet <>
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 

  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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