Kits including novel fluorescent derivitization reagents for labeling an aldehyde- and/or ketone-containing target substance in a sample are described. In one embodiment kits are provided the novel fluorescent derivitization reagents of which have the following formula: wherein Q is carbonyl, thiocarbonyl, or sulfonyl, and R5 is -L-Z; L is arylene, or a C1-6 perfluoroalkylene; Z is a carbonyl hydrazide, hydrazide, sulfonyl hydrazide, or a thiocarbonyl hydrazide; R11-R14 are independently H, C1-16 alkyl, C1-6 alkylamino, amino, or halogen; and R21-R24 are independently H, C 1-6 alkyl, C 1-6 alkoxy, C1-6 perfluoroalkyl, C1-6 alkylamino, di(C2-12-alkyl)amino, amino, carboxy, cyano, halogen, hydroxy, nitro, phenyl, sulfo, or -L-Z. The kits and reagents described are particularly useful for labeling glycoproteins or glycopeptides, nucleic acids, and lipopolysaccharides in electrophoresis gels.