Novel fluorescent derivitization reagents are described that are suitable for coupling to biomolecules that contain aldehyde or ketone functional groups. In one embodiment is provided reagents that have the following formula: ##STR1##

wherein Q is carbonyl, thiocarbonyl, or sulfonyl, and R⁵ is -L-Z; L is arylene, or a C_1-6 perfluoroalkylene, or a single covalent bond; Z is a carbonyl hydrazide, hydrazide, sulfonyl hydrazide, or a thiocarbonyl hydrazide; R¹¹-R¹⁴ are independently H, C_1-6 alkyl, C_1-6 alkoxy, C_1-6 perfluoroalkyl, C_1-6 alklyamino, di(C_2-12alkyl)amino, amino, carboxy, cyano, halogen, hydroxy, nitro, phenyl, or sulfo; and R²¹-R²⁴ are independently H, C_1-6 alkyl, C_1-6 alkoxy, C_1-6 perfluoroalkyl, C_1-6 alklyamino, di(C_2-12-alkyl)amino, amino, carboxy, cyano, halogen, hydroxy, nitro, phenyl, sulfo, or -L-Z. The method of treating a sample with the derivativization reagents is described. The reagents are particularly useful for labeling glycoproteins or glycopeptides, nucleic acids, and lipopolysaccharides in electrophoresis gels.