Preparation and analytical characterisation of pure fractions of cellooligosaccharides.

In the present work, a viable protocol was developed to prepare monodisperse cellooligomers up to a degree of polymerisation (DP) of 20. Peracetylated cellooligosaccharides were obtained from cellulose by acetolysis and subsequently purified by Normal Phase-High Performance Liquid Chromatography using toluene, ethyl acetate and acetone as eluents. In addition, we demonstrated how to efficiently monitor the purity and dispersity of the obtained compounds by High Performance Thin Layer Chromatography, Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry and Nuclear Magnetic Resonance. With this approach, it is possible to isolate cellooligomer standards up to DP 20 on a preparative scale (dozens of mg). The column chromatographic separation proved to be robust over several months and to be scalable from a analytical to a preparative column. The isolated oligomer standards allow a more precise description of cellooligomer distributions typically emerging from biorefinery process streams after hydrolysis of lignocelluloses. They can be used to calibrate the oligomeric region in size-exclusion chromatography where light scattering detection fails due to limited scattering intensities.