PREPARATION OF FEULGEN STAIN

©David B. Fankhauser, Ph.D.,
Professor of Biology and Chemistry
University of Cincinnati Clermont College,
Batavia OH 45103
Feulgen stain should be
straw colored when
freshly prepared.

This page has been accessed Counter times since 30 December 2004. 
rvsd 4 Jan 1994, latest revision 22 Jan '96, 3 Jan '98, 2 Jan 03
The tips have been
stained red with
Feulgen stain

 
 
fuchsin (magenta I)
This stain contains fuchsin or magenta I, a decolorized dye which has a strong affinity for DNA, producing a red color in its presence. Also called "rosaniline," is an aniline dye which consists of three aniline rings, one meta-methylated, para-attached to a central carbon. It's positively charged nitrogen is attracted to and stains the negatively charged PO4 groups in the DNA backbone. 

It is nearly colorless until it reacts with the PO4 which turns it red.

For 30 mL of the stain:
 

.
STAGE OPERATION
1. Weigh Weigh out 150 mg of Basic Fuchsin into 250 mL beaker.
2. Dissolve Pour 30 mL boiling dH2O over the Basic Fuchsin, swirl to dissolve.
3. Cool and filter. Cool to 50C, filter through Whatman No. 1 paper.
4. Acidify Add 4.5 mL 1N HCl, mix. (Caution: corrosive acid)
5. Decolorize Dissolve 0.45 g K2S2O5 (potassium metabisulfite) to decolorize the solution. 
Set in dark for 24 hours to bleach.
6. FilterDecant or filter through activated charcoal (e.g., Norit) to further clarify (if desired).
7. Storage Store in light-proof bottle in refrigerator. (I.e. wrap in aluminum foil to exclude light.)
NOTE:
It looks innocent because of its light straw color before it reacts with PO4 ,
but it will stain you seriously if you get in on your hands or clothes!

[Fuchsin(e) Acid is related, but meta-sulfonated on all three aniline rings.]