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Pyridylamination is a versatile method for fluorescence labeling of oligosaccharides. The technique affords sensitive detection of saccharides with reducing termini and high-resolution separation by high-performance liquid chromatography. The conventional method, based on a liquid-phase reaction, has been extensively used in various aspects of glycobiology and glycotechnology. Unfortunately, the necessity for removing excess 2-aminopyri-dine makes the technique both laborious and time-consuming. Furthermore, removal of excess reagent can result in a significant loss of short saccharide components. In the present paper, we report an alternative methodology based on a 'gas-phase' reaction, in which dried saccharides are reacted with vaporized 2-aminopyridine. The resultant Schiff base was also reduced in the gas phase within the same reaction microtube using a purpose-built device. The newly developed procedure was applied to both monosaccharide (GlcNAc) and oligosaccharides (isomalto-oligosaccharides) at quantitative yields with no requirement to remove excess reagent. The acid-labilesialyl linkages of ([alpha]-2-6-disialobiantennary oligosaccharides proved to be fully stable during the procedure. The developed method was also successfully applied to profiling N-linked oligosaccharides liberated from glycoproteins by hydrazinolysis and, thus, should contribute to various fields of glycomics.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), has been used for structure characterization of 1-aminopyrene-3,6,8-trisulfonate (APTS)-derivatized oligosaccharides previously separated by capillary electrophoresis (CE). The resolved components were first isolated by employing an automated high-resolution fraction collector. Using on-probe sample cleanup with a cation-exchange resin and a matrix mixture of (1:1) 6-hydroxypicolinic acid and 3-hydroxypicolinic acid, APTS-labeled oligosaccharides were successfully detected by MALDI-TOF MS in the negative ionization mode. Each APTS-labeled oligosaccharide produced single [[M - H].sup.-1] peaks. Detection limits for standard APTS-derivatized oligosaccharide (maltoheptaose) were down to 30 fmol. APTS labeled maltooligosaccharides and various standard carbohydrates were separated and collected by CE, followed by molecular weight determination with MALDI-TOF MS. The mass spectral characterization enhances the power of the CE analysis of oligosaccharides.