High performance size‐exclusion chromatography of anionic polymers in aqueous solutions

Abstract

SynopsisThe applicability of high performance size-exclusion chromatography was tested for anionic polymers with a new type of column. It was found that a solvent salt concentration of 0.1M and an elevated temperature (60°C) prevented adsorption of the polystyrene sulfonate standards on the column packing. The calibration curve and the effect of the concentration on the retention volume remained, however, column-dependent. We concluded also that the use of the column was restricted to the linear range of the calibration curve and to concentrations below 1 mg mL-' for the highest molecular weight standards. The influence of the flow rate (below 1 mL min-') on the retention volume was negligible. The main cause of errors when the universal calibration technique is used originated in the experimental determination of the intrinsic viscosities of the standards. The combination of the errors on the viscosity and on the experimentally determined retention volume easily introduced an error of 15% on the determined molecular weight of the sulfated polysacchaxide ic-carrageenan. The use of the universal calibration method for an exact molecular weight determination of anionic natural polymers is therefoq? still questionable.

Molecular weight distribution of carrageenans studied by a combined gel permeation/inductively coupled plasma (GPC/ICP) method

“…In addition, their mean MN was 245 kDa, and their mean MW was 530 kDa. These average molecular weight values were similar to those reported previously by some authors (Ekstrom 1985, Lecacheux et al 1985, Malfait et al 1990, Slootmaekers et al 1991.…”

“…Ekstrom (1985) tested eight samples of food-grade -carrageenan by using the system of GPC and the refractive index (RI) detector, and found the mean value of weight average molecular weights (MW) of these carrageenans was 167 kDa. Malfait et al (1990) reported that the MW of carrageenan was 303 kDa by using a similar system and that a broad peak of carrageenan was followed by a low molecular weight fraction. Lecacheux et al (1985) tried to use low angle laser light scattering (LALLS) as a detector.…”

Characterization of the Molar Masses of Hemicelluloses from Wood and Pulps Employing Size Exclusion Chromatography and Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry

“…Subsequently, the logarithms of the M p values determined by MALDI-MS were plotted as function of the corresponding retention volume ratios ( K ) obtained from the SEC separation (Figure ). These K values represent the ratio between the elution volume for a given hemicellulose and the elution volume for DMSO (used as the flow marker), according to the approach suggested by Malfait et al Calculation of the K value in this manner compensates for variations in the elution volume of a hemicellulose in connection with different SEC separations, which arise primarily from variations in flow rate.

6 Relationship between log M p (determined by MALDI-MS) and the relative retention volume ( K ) obtained with SEC for different hemicelluloses eluted with ammonium acetate or sodium hydroxide/acetate.

…”