Eosinol

Eosinol Y

Eosinol B

Property Data Common name Suggested name Other names     C.I. number C.I. name Class Ionisation Solubility aqueous Solubility ethanol Absorption maximum Colour Empirical formula Formula weight Eosinol Eosinol Y Eosine acid Tetrabromofluorescein Eosin Y, spirit soluble 45380.2 Solvent red 43 Fluorone Acid Slight Moderate 524 (Aldrich), 537 (Gurr) Red C20H8Br4O5 647.9

The coloured anion of eosin Y, and sometimes that of eosin B, are referred to as eosinol. They may be sold under the name eosin Y, spirit soluble and eosin B, spirit soluble. Eosin Y and eosin B themselves are the sodium salts of these anions. Compare the formulae of the eosinols above to that of fluorescein. Although eosinol is used to refer to the eosin Y anion primarily, the anion of many of the eosin homologues probably could be made in a similar fashion.

 

Making eosinol

• Make a strong (5% - 10%) solution of eosin Y in distilled water
• With a Pasteur pipette, slowly add concentrated hydrochloric acid
• Dye will begin to precipitate
• Add hydrochloric acid until precipitation stops
• Filter through Whatman #1 filter paper
• Wash the filtrate very well with distilled water
• Dry the filtrate at room temperature protected from dust
• Grind to a powder in a pestle and mortar
• Store in an appropriately capped and labelled container

Using eosinol
To use eosinol, simply add some to either a dehydrating ethanol or a xylene, until the fluid is adequately red. Some trial and error is needed to establish the correct amount. Prestain the nuclei with an alum hematoxylin, and blue. Then allow the sections to remain in the coloured fluid until stained darkly enough. Again, some trial and error is needed to determine the correct time. The dye is most valuable for difficult to stain tissues such as those from fetuses.

Reference
Susan Budavari, Editor, (1996)
The Merck Index, Ed. 12
Merck & Co., Inc., Whitehouse Station, NJ, USA

Aldrich chemical catalogue, 1992
Aldrich Chemical Company, Milwaukee, WI, USA.

Edward Gurr, (1971)
Synthetic dyes in biology, medicine and chemistry
Academic Press, London, England.