title: Effect of sample preparation methods on the analysis of dispersed polysaccharides by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.
abstract: Effect of sample preparation methods on the matrix-assisted laser desorption/ionization (MALDI) analysis of dispersed polysaccharides is reported. By using the conventional drop-drying method, the measured number-averaged molecular weights were found to differ significantly from the values obtained from gel-permeation chromatography (GPC). These discrepancies were found to increase as the average masses of the polysaccharides increased. To understand the impact of the sample preparation method on the MALDI measurement, a dispersed dextran sample was separated into ten narrow-distribution fractions. Mixtures of different mass fractions were prepared and analyzed by using different mixing and preparation methods. By using the ratio of the signal intensity for the low-mass fraction to that of the high-mass fraction as an indicator, the impact of sample preparation conditions on the enhancement of low-mass components (or suppression of high-mass components) was determined. From the results obtained, it is postulated that the difference in solubilities between the low-mass and high-mass components for dispersed polymers might be large enough to induce an enhancement of low-mass components (or suppression of high-mass components) at the surface of the crystals during sample crystallization in the drop-drying method.
authors.affiliation: Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: P K
authors.initials: PK
authors.lastname: Chan
authors.forename: T W
authors.initials: TW
authors.lastname: Chan
mesh_terms: D000465:Algorithms; D002850:Chromatography, Gel; D008970:Molecular Weight; D011134:Polysaccharides / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D011134:Polysaccharides