Ammonium 7-Fluoro-2,1,3-benzoxadiazole-4-sulfonate is a bifunctional fluorogenic reagent used to detect thiols in biological specimens and proteins. Ammonium 7-Fluoro-2,1,3-benzoxadiazole-4-sulfonate does not contain any fluorescence but relies on its high reactivity to thiols to attain low detection limits. In addition, liquid chromatography is useful in analyzing low molecular weight thiols by pre-column derivatization with Ammonium 7-Fluoro-2,1,3-benzoxadiazole-4-sulfonate, which is followed by fluorometeric detection at 515nm. Furthermore, the addition of tri-n-butylphosphine (TBP) enables Ammonium 7-Fluoro-2,1,3-benzoxadiazole-4-sulfonate to react with thiols in soft metals.