Many important crop and forage plants accumulate polymeric water-soluble carbohydrates as fructooligosaccharides (or fructans). We have developed an improved method for the analysis of the full fructan complement in plant extracts based on porous graphitized carbon chromatography coupled to negative electrospray ionization mass spectrometry. By the use of profile data collection and multiple charge state ions, the effective mass range of the ion trap was extended to allow for the analysis of very high-molecular-weight oligosaccharides. This method allows the separation and quantification of isomeric fructan oligomers ranging from degree of polymerization (DP) 3 to DP 49.