In Situ Size Exclusion Chromatographic NMR of Sunset Yellow FCF in Solution

2016

RSC Adv.

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Diffusion NMR is potentially a routine tool in the analysis of mixtures, from industrial and synthetic outputs to natural products. However, the technique struggles to resolve species of similar size. Matrix-assisted DOSY offers a flexible approach to resolving such ambiguities on the basis of the chemical structures involved and on their interactions with a larger co-solute or matrix. The use of chromatographic supports, surfactants and polymers, in particular, is illustrated. The resolution of a wide range of different analyte mixtures, on the basis of differences in chemical structure and in stereochemistry, is demonstrated.

Section: Use Of Chromatographic Supportsmentioning

confidence: 99%

Matrix-assisted diffusion-ordered spectroscopy

Evans

2016

RSC Adv.

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“…Recently, we have extended the concept of chromatographic NMR to the use of size‐exclusion stationary phases . These phases comprise a porous material, typically based on cross‐linked dextran, with pore sizes on the order of 10–100 nm.…”

Section: Introductionmentioning

confidence: 99%

Size‐exclusion chromatographic NMR under HR‐MAS

Alcalde

Anderson

Magnetic Reson in Chemistry

2016

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The addition of stationary phases or sample modifiers can be used to modify the separation achievable in the diffusion domain of diffusion NMR experiments or provide information on the nature of the analyte-sample modifier interaction. Unfortunately, the addition of insoluble chromatographic stationary phases can lead to line broadening and degradation in spectral resolution, largely because of differences in magnetic susceptibility between the sample and the stationary phase. High-resolution magic angle spinning (HR-MAS) techniques can be used to remove this broadening. Here, we attempt the application of HR-MAS to size-exclusion chromatographic NMR with limited success. Observed diffusion coefficients for polymer molecular weight reference standards are shown to be larger than those obtained on static samples. Further investigation reveals that under HR-MAS it is possible to obtain reasonably accurate estimates of diffusion coefficients, using either full rotor synchronisation or sophisticated pulse sequences. The requirement for restricting the sample to the centre of the MAS rotor to ensure homogeneous magnetic and RF fields is also tested. Copyright © 2016 John Wiley & Sons, Ltd.

“…We have demonstrated that the observed changes in diffusion properties of a series of polymer molecular weight reference standards is consistent with size‐exclusion behaviour, in which smaller polymers show greater retardation in their diffusion than larger polymers . These systems have also been used to investigate aggregating systems, with assemblies of the azo‐dye sunset yellow partitioning between the pores in the stationary phase and the free solution surrounding the particles, depending on the overall aggregate size . In both cases, the large size of the analyte molecules or assemblies means that the addition of the stationary phase causes only minor additional line broadening …”

Section: Introductionmentioning

confidence: 99%

“…[15] These systems have also been used to investigate aggregating systems, with assemblies of the azo-dye sunset yellow partitioning between the pores in the stationary phase and the free solution surrounding the particles, depending on the overall aggregate size. [16] In both cases, the large size of the analyte molecules or assemblies means that the addition of the stationary phase causes only minor additional line broadening. [15,16] In this paper, we demonstrate extending of the range of applicability of in situ size-exclusion chromatographic NMR to polymer mixtures.…”

Section: Introductionmentioning

confidence: 99%

Size‐exclusion chromatographic NMR of polymer mixtures

Alcalde

Joyce

Magnetic Reson in Chemistry

2014

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The use of chromatographic stationary phases or solvent modifiers to modulate diffusion properties in NMR experiments is now well established. Their use can be to improve resolution in the diffusion domain or to provide an insight into analytemodifier interactions and hence the chromatography process. Here we extend previous work using size-exclusion chromatographic (SEC) stationary phases to the investigation of polymer mixtures. We demonstrate that similar diffusion modulation behaviour is observed with an SEC stationary phase which can be understood in terms of size-exclusion behaviour.3