Consecutive determination of softwood kraft lignin structure and molar mass from NMR measurements

Holzforschung ◽  
2017 ◽  
Vol 71 (7-8) ◽  
pp. 563-570 ◽  
Author(s):  
Jerk Rönnols ◽  
Anna Jacobs ◽  
Fredrik Aldaeus
Keyword(s):  
Molar Mass ◽  
Industrial Applications ◽  
Size Exclusion ◽  
Ionization Time ◽  
Flight Mass Spectrometry ◽  
Exclusion Chromatography ◽  
Pfg Nmr ◽  
Softwood Kraft Lignin ◽  
Good Agreement

Abstract The general molecular properties and in particular, the molar mass of lignin are of central importance for industrial applications, as these data govern important thermal and mechanical characteristics. The focus of the present paper is pulsed field gradient-nuclear magnetic resonance (PFG-NMR), which is suitable for determination of lignins’ weight-average molar mass, based on diffusion constants. The method is calibrated by lignin fractions characterized by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). It could be demonstrated on a set of softwood kraft lignins that the PFG-NMR approach gives results in very good agreement with those obtained using conventional size exclusion chromatography (SEC).

scholarly journals A Novel Synthesis of Poly(Ester-Alt-Selenide)s by Ring-Opening Copolymerization of γ-Selenobutyrolactone and Epoxy Monomer

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1203 ◽  
Author(s):  
Ya’nan Wang ◽  
Xiaofang Lin ◽  
Zhengbiao Zhang ◽  
Jian Zhu ◽  
Xiangqiang Pan ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Effective Means ◽  
Linear Structure ◽  
Size Exclusion ◽  
Ionization Time ◽  
Flight Mass Spectrometry ◽  
Epoxy Monomer ◽  
Polymerization System ◽  
Exclusion Chromatography

Ring-opening copolymerization (ROCOP) is an effective means to prepare functionalized polyester. In this work, a type of selenide-containing polyesters with controllable structure, molecular weight, and molecular weight distribution was successfully prepared by ROCOP of γ-selenobutyrolactone and epoxy compounds. The influence of the catalyst, solvent, and reaction temperature on the reaction efficiency was examined. Then, kinetic study was investigated under an optimized condition. The structure of the copolymers was carefully characterized by nuclear magnetic resonance (NMR), 1H NMR, 13C NMR, and 77Se NMR, Matrix-assisted laser-desorption-ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and size exclusion chromatography (SEC). The resulting polymers showed a linear structure with a sequence regulated backbone repeating unit of ester-selenide. On this basis, some typical epoxides were investigated to verify the scope of the polymerization system. Due to the “living”/controlled characteristics of this ROCOP, multiblock, amphiphilic, and stereotactic copolymers could be prepared with a pre-designed structure. As expected, the selenide-containing amphiphilic copolymer could self-assemble to micelles and showed an oxidative response.

Analysis of carbohydrates in Fusarium verticillioides using size-exclusion HPLC – DRI and direct analysis in real time ionization – time-of-flight – mass spectrometry (DART-MS)

2016 ◽  
Vol 8 (3) ◽  
pp. 673-681 ◽  
Author(s):  
Ethan S. Roberts ◽  
Beth A. Boudreau ◽  
Daren W. Brown ◽  
Kristi L. McQuade ◽  
Edward E. Remsen
Keyword(s):  
Mass Spectrometry ◽  
Real Time ◽  
Fusarium Verticillioides ◽  
Time Of Flight ◽  
Direct Analysis ◽  
Size Exclusion ◽  
Ionization Time ◽  
Flight Mass Spectrometry ◽  
Exclusion Chromatography ◽  
Size Exclusion Hplc

Direct analysis in real time – time of flight – mass spectrometry (DART-TOF-MS) and size-exclusion chromatography (SEC) are used to analyze carbohydrates inF. verticillioides, such as trehalose.

Mark–Houwink–Sakurada coefficients determination for molar mass of silk fibroin from viscometric results. SEC-MALLS approach

RSC Advances ◽  
2016 ◽  
Vol 6 (44) ◽  
pp. 38071-38078 ◽  
Author(s):  
D. Pawcenis ◽  
M. Syrek ◽  
M. A. Aksamit-Koperska ◽  
T. Łojewski ◽  
J. Łojewska
Keyword(s):  
Bombyx Mori ◽  
Size Exclusion Chromatography ◽  
Silk Fibroin ◽  
Molar Mass ◽  
Size Exclusion ◽  
Exclusion Chromatography

The results on the changes of average molar masses inBombyx morifibroin with use of size exclusion chromatography and viscometry are presented in terms of the determination of Mark–Houwink–Sakurada coefficients, which are lacking in the literature.

scholarly journals Size-exclusion chromatography of cellulose: observations on the low-molar-mass fraction

Cellulose ◽  
2020 ◽  
Vol 27 (16) ◽  
pp. 9217-9225
Author(s):  
Leena Pitkänen ◽  
Herbert Sixta
Keyword(s):  
Mass Distribution ◽  
Size Exclusion Chromatography ◽  
Mass Fraction ◽  
Molar Mass ◽  
Accurate Determination ◽  
Size Exclusion ◽  
Molar Mass Distribution ◽  
Universal Method ◽  
Exclusion Chromatography

AbstractAccurate determination of molar mass distribution for disperse cellulose samples has proved to be a challenging task. While size-exclusion chromatography coupled to multi-angle light scattering (MALS) and differential refractive index (DRI) detectors has become the most commonly used method for molar mass determination of celluloses, this technique suffers low sensitivity at the low-molar mass range. As discussed here, the universal method for accurate molar mass distribution analysis of cellulose samples not exists and thus thorough understanding on the differences of the various methodological approaches is important. In this study, the focus is in the accurate determination of the low-molar mass fraction. The results obtained by combining the two calibration strategies, MALS/DRI for polymeric region of a cellulose sample and conventional calibration for oligomeric region, was compared to the results obtained using only MALS/DRI (with extrapolation of the curve where signal-to-noise of MALS is low). For birch pulp sample, the results from the two approaches were comparable; it should be highlighted, however, that MALS/DRI slightly overestimates the molar masses at the low-molar-mass region.

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