Pararosaniline, Basic Red 9, or C.I.

Colour Index International

Colour Index International is a reference database jointly maintained by the Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists. It was first printed in 1925 but is now published exclusively on the web...

 42500 is a magenta dye

Dye

A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....

 having chemical formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 ₁₉₁₈₃. It is one of the four components of basic fuchsine

Fuchsine

Fuchsine or rosaniline hydrochloride is a magenta dye with chemical formula C20H19N3·HCl. There are other similar chemical formulations of products sold as fuchsine, and several dozen other synonyms of this molecule....

. (The others are rosaniline, new fuchsine

New fuchsine

New fuchsine, new fuchsin, Magenta III, Basic Violet 2, or C.I. 42520 is a magenta dye having chemical formula 22243. It is one of the four components of basic fuchsine, and one of the two that are available as single dyes. New fuchsine can be used for staining acid fast organism, e.g...

 and magenta II.) Pararosaniline, which is sold as a single dye, may make the best Schiff's reagent. It is the only basic fuchsine component suitable for making the aldehyde-fuchsine stain for pancreatic islet beta cells