Precise Determination of the Band-Broadening Function for the Size-Exclusion Chromatography using Multi-Angle Light Scattering and Mass Spectrometric Measurements on Polymers.

Modelling molecular weight changes induced in polydimethylsiloxane by gamma and electron beam irradiation

Molecular weight (MW) data for shale oils, including molecular weight distributions (MWDs) as well as average MWs, is difficult to find. A thorough literature review of MW data for shale oils from different pyrolysis processes, found scattered across a wide range of topics (or papers on various topics) and analyzed here, was carried out as part of the study. However, because the data are for oils produced under different conditions, and the exact pyrolysis conditions are sometimes not fully described, then the MW values generally are not directly comparable. Therefore, in the experimental part of the current study, average MWs and MWDs were measured for shale oils from four different oil shales (Green River in the western United States, Attarat Umm Ghudran in Jordan, Kukersite in Estonia, and Dictyonema in Estonia) obtained by retorting under identical pyrolysis conditions, using a standardized Fischer assay method. The main goal of the study, to measure the MWDs of the Fischer assay oils, was accomplished using size exclusion chromatography (SEC). The MWD data obtained was also compared to that from atmospheric solids analysis probe mass spectroscopy (ASAP MS). In addition, MWDs of industrial Kukersite shale oil from Kiviter and Galoter processes were evaluated for comparison. The MWDs of Fischer assay shale oils obtained in the current study ranged from 100 g mol–1 to 600 g mol–1. While the oils show comparable average MW values, the parameters describing the width and shape of MWDs were more dependent on the parent oil shale.

Simultaneous determination of protein aggregation, degradation, and absolute molecular weight by size exclusion chromatography–multiangle laser light scattering

Background:Many exopolysaccharides from the endophytes in medicinal plants possess various potential bioactivities.Materials and Methods:The endophytic fungus JY25 was isolated from the leave of the Chinese medicinal plant Gynostemma pentaphylla and identified as Chaetomium sp. by its phylogenetic and physiological analysis. One exopolysaccharide (EPS) fraction was isolated from the fermentation broth by ethanol precipitation and purified by gel filtration chromatography on Sepharose CL-6B. The molecular characteristics were examined by GC-MS, FT-IR, and multiangle laser light scattering (MALLS).Results:The monosaccharide composition analysis indicated that the purified EPS was mainly composed of glucose, mannose, arabinose, and galactose with the molecular ratio of 78.29: 8.99: 8.64: 4.08. FT-IR spectral analysis of the purified EPS revealed prominent characteristic groups, such as carbonyl bond, pyranose ring, and so on. The weight-average molar mass and the polydispersity ratio of the EPS were revealed to be 1.961×104 g/mol and 1.838, respectively. Furthermore, thermo gravimetric analysis (TGA) indicated that the degradation temperature of the purified EPS was 305° C. The purified EPS from the endophytic fungus Chaetomium sp. displayed antioxidant and antiproliferative activities.Conclusion:The results demonstrated that the EPS could be used as a healthful food and material source in pharmaceutical industries.SUMMARY An exopolysaccharides (EPS) with antioxidant and antiproliferative activities from an endophytic fungus Chaetomium sp. was reported. Abbreviations used: ANOVA: Analysis of variance; DPPH: 2,2-diphenyl-1-picrylhydrazyl; EPS: Exopolysaccharide; FT-IR: Fourier transform infrared spectroscopy; GC-MS: Gas chromatography–mass spectrometry; Mw: Mass weight; MALLS: Multiangle laser light scattering; SEC: Size Exclusion Chomatography; SPSS: Statistical Package of the Social Science; TGA: Thermo gravimetric analysis; TFA: Trifluoroacetic acid.

Characterization of branched ultrahigh molar mass polymers by asymmetrical flow field-flow fractionation and size exclusion chromatography

Characterization of enzymatically synthesized amylopectin analogs via asymmetrical flow field flow fractionation

The molecular weight distribution (MWD) of commercial suspension grade poly(vinyl chloride) (PVC) resins with K values from 50 to 93 and mass grade PVC resins with K values from 58 to 68 has been determined by size exclusion chromatography (SEC), using literature Mark‐Houwink coefficients. The MWD is characterized by the number average molecular weight ( M n ), the weight average molecular weight ( M w ) and the polydispersity ( M w /M n ). Our results for M w are consistent with recently published data, but we find different results for M n and consequently for M w /M n . The polydispersity of PVC increases with increasing K value. This effect can be explained by two mechanisms. The first mechanism is a reduced terminating reaction rate between two growing polymer chains (disproportionation) at higher molecular weight owing to the reduced mobility of the polymer chains. The second mechanism is long‐chain branching of molecules with high molecular weight which lets the molecules grow at two ends. For two examples graphs of the measured MWD are compared with the theoretically expected MWD.

Keywords: biopolymer, gelatine, dextran, PEO, phase separation, polydispersity, molar mass distribution, SEC-MALLS, CSLM The temperature-composition phase diagram of aqueous solutions of gelatine and dextran, which show liquid/liquid phase segregation, were explored at temperatures above the gelation temperature of gelatine. It turned out that the compositions of coexisting phases show practically no dependence on temperature between 40oC and 80oC. Also, the total polymer concentration at which phase separation occurred was found to be nearly independent on temperature. These observations suggest an entropy driven phase separation. Phase separation is found to be accompanied by strong fractionation of the molar mass distribution in the two phases. Molar mass distributions in coexisting phases were investigated using Size Exclusion Chromatography with MultiAngle Laser Light Scattering. The molar mass of the native material and concentration appeared to be the only factors that affected the final molar mass distributions, temperature having no effect. The results show that in the molar mass range where fractionation is the strongest, i.e. roughly below the maximum in the distribution, fractionation is governed by a Boltzmann factor , where DG denotes the free energy involved in transferring a polymer with a certain length from the enriched to the depleted phase, and in this case turns out to be proportional to the molar mass. The phase behaviour of aqueous mixtures of poly(ethylene oxide) (PEO) and dextran is also studied. From the temperature dependence we conclude that the phase separation between PEO and dextran is partly caused by sterical interactions. From the equilibrium phase volumes of the phase separated mixture and the shape of the temperature-composition phase diagram of PEO and dextran we conclude that also the decrease of solvent quality of water for PEO at increasing temperatures is involved. It is suggested that the characteristics of the PEO-water interaction can affect the degree of fractionation. This suggestion is based on the observation that the degree of fractionation is not a simple exponential function of the molar mass. Adsorption of high molar mass dextran at the interface between gelatine and dextran during the phase separation of aqueous mixtures of these two polymers is also studied. This adsorption is observed after macroscopic phase separation as well as during the phase separation. In the last case, the system is studied with Confocal Scanning Light Microscopy. For this purpose, the dextran is covalently labelled with fluorescein 5-isothiocyanate (FITC). It turns out that the adsorption of high molar mass dextran is highly affected by the labelling. The adsorption of labelled dextran leads to a stable film between the two coexisting phases, thus preventing dextran droplets to coalesce. If the degree of labelling increases above a certain level, the labelled dextran does not lead to a stable film, but is preferentially present in the gelatine-rich phase.

Distribution analysis of ultra-high molecular mass poly(ethylene oxide) containing silica particles by size-exclusion chromatography with dual light-scattering and refractometric detection

Characterisation of kappa- and iota-carrageenan coils and helices by MALLS/GPC

Characterisation of gum from Acacia senegal trees of different age and location using multidetection gel permeation chromatography

Determination of Modification Degree of Succinylated Gelatin by Size Exclusion Chromatography Coupled with Multi Angle Laser Light Scattering

Foreword

The property profile of cellulose derivatives dissolved in aqueous solvents is not only dependent on the chemical composition (average‐, molar‐ or regiospecific degree of substitution, as well as the substitution along the chain), solvent, temperature and concentration but also on the molar mass and the particle size. All this information can be obtained from the Mark‐Houwink‐Sakurada‐relationship ([;gh]‐M‐) or the RG‐M‐relationship, if these are at hand. These relationships are suitable for a specific degree of substitution. The RG‐M‐relationship has only been determined and published for a few water‐soluble cellulose derivatives.The prerequisite is the availability of a homologous series of samples with the same chemical composition. In this paper it is shown that only the ultrasonic degradation is able to create such a series.Due to the ability of coupled methods of analysis to acquiring absolute data, molar mass and particle size distributions have been compiled in recent years. Using such methods it was possible to determine molar mass and particle size distributions of several aqueous cellulose derivative solutions by combining a fractionation unit (size exclusion chromatography (SEC) or flow field‐flow fractionation (FFFF)) with multi angle laser light scattering (MALLS) for the detection of Mw and RG and concentration detection (DRI). Results for nonionic cellulose ethers, mixed cellulose ethers, ionic carboxymethyl cellulose, sulfoethyl cellulose, hydrophobically modified hydroxyethyl cellulose were obtained and are partially discussed with focus on the recovery of cellulose derivates after fractionation and the impact on the distribution functions.

Molar mass characterization of cellulose acetates over a wide range of high DS by size exclusion chromatography with multi-angle laser light scattering detection