Fluorescent dye that is water-soluble and forms stable Schiff Base with carbonyl group. Compared with Alexa Fluor 750, Fluorescent Dye 750-I is much brighter with absorption at 633nm. Fluorescence emission of Fluorescent Dye 750-I Hydrazide is well separated from that of other commonly used red fluorophores, such as TAMRA, Fluorescent Dye 647-I and R-phycoerythrin, making it ideal for multi-color labeling.