RE: Light Green Aqueous Mounting

From:Gary Gill

For general information:

SF in light green SF yellowish = Saurefarbstoff = acid dye

FCF in fast green FCF = for coloring food

Gary Gill

-----Original Message-----
From: J. A. Kiernan []
Sent: Thursday, August 08, 2002 8:36 AM
To: Linda Jenkins
Subject: Re: Light Green Aqueous Mounting

Linda Jenkins wrote:
> mounting medias.  It states that potassium acetate may be added
> to aqueous mountants  almost to the point of saturation to
> reduce the bleeding of cationic dyes, at the same time giving a
> pH of approximately 7.0.  So... I guess the question
> light green cationic?

No, it's an anionic dye, and potassium acetate will increase
bleeding into an aqueous medium. You would need to acidify
to reduce bleeding. But is it really necessary for you to
use an aqueous mountant? Why not dehydrate, clear, and 
mount in a resinous medium?

Light green (and also fast green FCF) is easily extracted 
from stained sections by water-alcohol mixtures. The only 
safe way to retain it is to dehydrate in 100% alcohol, then
clear and use a resinous medium. Even then, light green
will fade with long storage. The closely similar dye
fast green FCF can be used in exactly the same way but 
does not fade, so it's really better all round.
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1

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