Aceto-Carmine Chromosome Stain Recipe

There are several versions of this stain. An iron containing stain is often used because of the darker bluish-red color produced

Non-iron version

1. Heat a solution of 45% acetic acid (45ml glacial acetic acid/55ml of distilled water) to boiling
2. Add 0.5g of Carmine and continue heating for 15-20 minutes while stirring
3. Cool resulting solution
4. Filter to remove any precipitate

Iron containing version

1. Heat a solution of 45% acetic acid (45ml glacial acetic acid/55ml distilled water) to boiling. ALWAYS use caution and wear personal protective equipment when in the laboratory with concentrated acids (or any other time)
2. Add 0.5g of Carmine and continue heating for 15-20 minutes while stirring
3. Cool resulting solution
4. Filter to remove any precipitate
5. Separately make a solution of 45ml glacial acetic acid/55ml distilled water/5g Ferric oxide)
6. Slowly (dropwise) add the Ferric oxide solution to 50ml of the Carmine solution until a precipitate starts to appear
7. Promptly add 50ml of Carmine solution to the titrate mixture
8. Filter to remove any precipitate

Cautions: ALWAYS use caution and wear personal protective equipment when in the laboratory with concentrated acids (or any other time)! Always add acid slowly into water and do not add water into acid!