application： 8-Amino-2-naphthalenesulfonic acid can be used as a reactant to synthesize: Fe3O4/sulfonated polyaniline composite material via chemical oxidative polymerization with aniline in the presence of magnetite (Fe3O4) nanoparticles. Prismatic crystals of strychnine-8-ammonio-2-naphthalenesulfonate-water by heating with strychnine in water/ethanol solvent mixture. 5-amino-9-dialkylamino benzo[a]phenoxazine dyes (Nile blue analogs) by condensation with N-alkyl or N-sulfo-propyl 4-arylazo-substituted 3-hydroxyaniline.