Methods for monitoring trace levels of 4‐aminobiphenyl, 2‐naphthylamine, and their hydrochloride salts in waste water, microbiological growth media, potable water, human urine, and mouse blood utilizing spectrophotofluorometry (SPF) are described. The salient elements of the methods are extraction of the residues as the free amine with benzene, rapid cleanup on an alumina column, and quantification of the free amine in methanol via SPF. Potable water solutions of the salts are diluted with 0.01 N aqueous HCL and quantified directly by SPF. Ancillary analytical information concerning gas chromatography of the free amines, partitioning properties of the compounds between solvent pairs, their solubility and stability in water, and thin‐layer chromatographic data is presented. The compositions of various admixtures of 1‐ and 2‐naphthylamine or their salts were determined by using SPF with calculations based on simultaneous equations.