Product Description: BDP 581/591 carboxylic acid is a fluorescent dye (Ex=585 nm, Em=594 nm). BDP 581/591 carboxylic acid has a free carboxylic acid group, which can be catalyzed by a catalyst (such as EDC or HATU) to react with primary amines to form stable amide bonds. BDP 581/591 carboxylic acid is highly photostable and can be used for ROS detection.