Fuchsine base monohydrochloride (Rosaniline Base monohydrochloride) is a magenta dye and uses for acid-fast staining with carbol-fuchsin.

1. Carbol Fuchsin Staining Method

1. Prepare the carbol fuchsin solution, which consists of fuchsine and phenol.

2. Drop the dye solution on the sample on the slide.

3. Heat the sample and maintain a certain temperature (such as around 60°C) to allow the dye to penetrate the cell structure.

4. Stain for about 5-10 minutes.

5. Then use acid alcohol (usually 3% hydrochloric acid alcohol) to decolorize and remove unwanted staining.

6. Finally, use contrast staining such as methylene blue or Gram staining for final observation.

2. Acid-fast staining:

1. Because carbol fuchsin has a strong affinity with acid and alcohol, it is often used to stain acid-fast bacteria (such as Mycobacterium tuberculosis).

2. These bacteria can remain red during the staining process, while other bacteria are removed and appear blue or other colors.