Online LC-NMR – From an expensive toy to a powerful tool in polymer analysis

Hiller, Wolf; Sinha, Pritish; Hehn, Mathias; Pasch, Harald

doi:10.1016/j.progpolymsci.2013.10.001

Cited by 46 publications

(25 citation statements)

References 136 publications

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“…For that, MALS, differential refractive index (dRI), UV/Vis, and dynamic light scattering (DLS) are commonly applied [177]. Additional information on similar parameters could be delivered by differential viscometer [178], and structure and molecular composition can be further investigated by coupling AF4 to nuclear magnetic resonance (NMR) [179] and FT-IR [180].…”

Section: Separation Principlementioning

confidence: 99%

Size Separation Techniques for the Characterisation of Cross-Linked Casein: A Review of Methods and Their Applications

et al. 2018

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Abstract:Casein is the major protein fraction in milk, and its cross-linking has been a topic of scientific interest for many years. Enzymatic cross-linking has huge potential to modify relevant techno-functional properties of casein, whereas non-enzymatic cross-linking occurs naturally during the storage and processing of milk and dairy products. Two size separation techniques were applied for characterisation of these reactions: gel electrophoresis and size exclusion chromatography. This review summarises their separation principles and discusses the outcome of studies on cross-linked casein from the last~20 years. Both methods, however, show limitations concerning separation range and are applied mainly under denaturing and reducing conditions. In contrast, field flow fractionation has a broad separation range and can be easily applied under native conditions. Although this method has become a powerful tool in polymer and nanoparticle analysis and was used in few studies on casein micelles, it has not yet been applied to investigate cross-linked casein. Finally, the principles and requirements for absolute molar mass determination are reviewed, which will be of increased interest in the future since suitable calibration substances for casein polymers are scarce.

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Section: Separation Principlementioning

confidence: 99%

Size Separation Techniques for the Characterisation of Cross-Linked Casein: A Review of Methods and Their Applications

et al. 2018

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“…[47] The general setup of such an experiment is shown in Fig. 6; details on principles and applications are provided by a recently published review by Hiller et al [19] The separation and analysis of two different blends of isotactic (I) and syndiotactic (HS, S) PMMAs are presented in Fig. 7.…”

Section: Microstructure Analysis By Column-based Fractionationsmentioning

confidence: 99%

“…Fractionation methods can be efficiently coupled to infrared spectroscopy, [11,12] mass spectrometry (MS), [13][14][15][16][17] and nuclear magnetic resonance spectroscopy. [18,19] Most recent reviews on the coupling of Fourier transform infrared spectroscopy, Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and nuclear magnetic resonance (NMR) with different LC methods are presented in Hiller et al [19] , Pasch and Mautjana [20] , and Barner-Kowollik et al [21] Over the past decades, column-based fractionations have been used for solving a multitude of analytical problems, see some recent reviews in Chang 7 , Malik and Pasch…”

Section: Introductionmentioning

confidence: 99%

Advanced fractionation methods for the microstructure analysis of complex polymers

Pasch

2015

Polymers for Advanced Techs

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This review discusses some recent work on the microstructure analysis of complex polymers using advanced fractionation methods. Complex polymers are distributed in a number of molecular parameters including molar mass, chemical composition, molecular architecture, and microstructure. Molar mass and chemical composition analysis is typically conducted by a range of spectroscopic and chromatographic methods, size exclusion chromatography and high-performance liquid chromatography (HPLC) being the most important fractionation methods. It is shown that HPLC is also very sensitive regarding polymer microstructure and can be used for the fractionation of e.g. polymethacrylates, polyisoprene, and polybutadiene. The best approach to the quantitative analysis of microstructure distributions is the on-line coupling of the fractionation with 1 H nuclear magnetic resonance spectroscopy. The spectroscopic analysis of chromatographic fractions provides concentration profiles of the tactic units as a function of the chromatographic separation and can be used for both HPLC and size exclusion chromatography. Apart from column-based fractionations, channel-based fractionations such as thermal field flow fractionation are powerful tools for microstructure analysis of complex polymers. It has been shown very recently that thermal field flow fractionation is capable of fractionating polyisoprene and polybutadiene according to microstructure.

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“…The blend components were dissolved in TCB at 130 C. The SEC operating temperature was also 130 C. The NMR accessory was kept at a temperature of 120 or 130 C. Similar to ambient temperature LC-NMR, specific solvent signals must be suppressed [54]. The suppression of the three aromatic proton signals of the solvent was achieved by WET (water suppression through T 1 effects) suppression without adding a lock solvent.…”

Section: Analysis Of the Blendsmentioning

confidence: 99%