New fuchsine is used to dye polyacrylonitrile, paper, and leather.[citation needed] In biology, it can be used for staining acid-fast organisms, e.g. by Ziehl–Neelsen stain, and for making Schiff's reagent. As a primary amine, the dye can be diazotized in the laboratory, and the resulting diazonium salt used as a trapping agent in enzyme histochemistry.[3]