Novel method and reagents for generating reversibly tagged saccharides, aldehydes, carboxyl acids, or orthoacetates useful in analytical and diagnostic applications are disclosed. Saccharides are coupled at the reducing end to tagging moieties comprising a reagent selected from a ortho-diaminobenzoic (DAB)-peptide, an aldo-imidazole or N-methylated aldo-imidazole, or an ortho-phenyldiamine (OPD) or substituted OPD. The tagged saccharide further comprising detectable or functional groups coupled to the tagging moiety are provided. Kits and reagents for chromatography and mass spectrometry are disclosed.