[Histonet] formalin pigment

[Paul Bradbury]

The situation you are decribing, with old solutions of formaldehyde, 
long storage times ususally associated with morgue specimens, is a 
classical formalin pigment-producing scenario.

To confirm that the pigment is formalin pigment (correctly known as acid 
formol hematin) just examine  a section containing the pigment using a 
polarized light microscope. Formalin pigment is birefringent and will 
appear bright on a dark background. No other common pigments are 
birefringent. Also if it tends to be more concentrated in areas where 
there are numerous red blood cells, in blood vessels, in spleen, etc., 
you can be pretty sure you are dealing with formalin pigment.

To get rid of the pigment from the sections, treat the de-waxed sections 
with saturated alcoholic picric acid for about 30 minutes, then wash the 
sections very well to remove the yellow staining, then stain as usual.

Paul Bradbury
Kamloops, BC, Canada


MARY JOHNSON wrote:

>hi histonette, I am having problems with formalin pigments, I am sure it is because of the out dated Formaldehyde that the moruge is using. Can any one help me prove this 
>  what test can i use? Is the paper pH ok to prove this. I need help with this one
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