Characterization of water-soluble hemicelluloses from spruce and aspen employing SEC/MALDI mass spectroscopy.
Partly depolymerized hemicelluloses isolated from wood chips of spruce and aspen employing microwave treatment were resolved using size-exclusion chromatography (SEC) into oligo- and polysaccharide fractions containing components with a narrow range of sizes, as determined by MALDI mass spectroscopy. The degree of substitution with acetyl moieties (DS) was also calculated on the basis of the MALDI-MS spectra obtained prior to and following deacetylation. For spruce hemicelluloses, the low molecular mass fraction contained small arabino-4-O-methylglucuronoxylan oligosaccharides, with DP values ranging from 4 to approximately 20, separated primarily on the basis of their charge density. The fraction eluted last consisted of an O-acetyl-(galacto)glucomannan polysaccharide of peak-average DP value (DP(p)) 14. The degree of substitution with acetyl groups (DS) decreased with decreasing DP, a value DS of 0.39 being obtained for the fraction with DP(p) 12. For the aspen hemicelluloses, the SEC fractions eluted first contained an acidic O-acetyl-4-O-methylglucuronoxylan polysaccharide with DP ranging from 10 to approximately 28 and an average DS of approximately 0.75. The fractions eluted last consisted of oligosaccharide mixtures composed primarily of small neutral O-acetyl-xylooligosaccharides (DP(p) 6, DS 0.41), together with minor quantities of an O-acetyl-glucomannan.
Jacobs
Anna
A
STFI, Swedish Pulp and Paper Research Institute, PO Box 5604, SE-114 86 Stockholm, Sweden.
Lundqvist
Jon
J
Stålbrand
Henrik
H
Tjerneld
Folke
F
Dahlman
Olof
O
D000107:Acetylation; D002850:Chromatography, Gel; D008351:Mannans / Q000032:analysis; D009844:Oligosaccharides / Q000032:analysis; D028222:Picea / Q000737:chemistry*; D011134:Polysaccharides / Q000032:analysis*; D031308:Salicaceae / Q000737:chemistry*; D012995:Solubility; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014990:Xylans / Q000032:analysis
D008351:Mannans; D009844:Oligosaccharides; D011134:Polysaccharides; D014990:Xylans; C007916:hemicellulose