fuchsin

Fuchsin, also called fuchsine, is a magenta-colored dye belonging to the triarylmethane family. It is typically marketed as a mixture of related dyes derived from coal tar, often referred to as basic fuchsin or rosaniline-based dyes. The compound exists as salts (for example, fuchsin hydrochloride) that are water-soluble and exhibit a deep magenta color in solution.

Historically used as a general dye in textiles and as a staining agent in biology, fuchsin remains in use in microbiology and histology for specific staining procedures. The most well-known application is carbol fuchsin, a staining solution that contains basic fuchsin and phenol and is used in the Ziehl-Neelsen acid-fast stain to identify mycobacteria. In addition, it has served in various differential staining procedures due to its strong color and metachromatic properties.

Chemically, fuchsin is not a single pure compound but a family of related triarylmethane dyes. Its staining properties depend on pH and the particular salt form, enabling it to act as a basic dye that binds to acidic cellular components, such as nucleic acids and certain cell walls.

Safety: Fuchsin compounds can be irritants and sensitizers. Handling should include gloves and eye protection, with proper ventilation. Used solutions should be disposed of according to local regulations for dyes and hazardous chemicals.

See also: carbol fuchsin; rosaniline; pararosaniline; magenta; triarylmethane dyes.