Naphthol AS-OL acetate (NAA) is a chromogenic substrate that is used in food testing, diagnostics and environmental testing. NAA has been shown to be an excellent ligand for the determination of aminoglycoside activity. It also has a high fluorescence yield, making it ideal for use as a fluorogenic substrate in chemiluminescent assays. This product has been found to be suitable for use with culture media containing tryptophan or tyrosine. Naphthol AS-OL acetate is an excellent high purity and high quality chemical reagent for conjugation with proteins and peptides.