Synthesis and testing of a novel fluorescence label for carbonyls in carbohydrates and cellulosics

A carbonyl-selective fluorescence label 5 for the detection of oxidized gro ups has been synthesized by an expeditious three-step sequence. The fluorop hore carbazole and the reactive aminoxy group, which binds to carbonyls as an oxime, were tethered by a diethylene glycol spacer. The label allows det ection of minute amounts of oxidized functionalities in oligosaccharides an d cellulosics under the relatively harsh conditions of GPC separation, with out fluorescence interference with light scattering (MALLS) detection. Synt hetic keto sugars have been used to optimize the derivatization reaction.