Generalized Universal Molecular Weight Calibration Parameter in GPC

Hamielec, A. E.; Ouano, A. C.

doi:10.1080/01483917808068382

Cited by 115 publications

(63 citation statements)

References 7 publications

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“…While it has been shown that the universal calibration assumption is valid for a wide variety of molecular architectures, [29][30][31] it should be noted that this may not be completely reliable for glycogen; however, all significant conclusions reviewed here are independent of any inaccuracy in the size axis that might arise from any breakdown in the universal calibration assumption. Furthermore, because a complex branched polymer such as glycogen can have molecules of the same molecular size with different branching structures and thus potentially different molecular weights, a molecular weight distribution cannot in principle, not just in practice, be obtained for such molecules, whatever the detector.…”

Section: Glycogen Size Characterisationmentioning

confidence: 90%

The Molecular Size Distribution of Glycogen and its Relevance to Diabetes

Gilbert

Sullivan

2014

Aust. J. Chem.

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Glycogen is a highly branched polymer of glucose, functioning as a blood-glucose buffer. It comprises relatively small b-particles, which may be joined as larger aggregate a-particles. The size distributions from size-exclusion chromatography (SEC, also known as GPC) of liver glycogen from non-diabetic and diabetic mice show that diabetic mice have impaired a-particle formation, shedding new light on diabetes. SEC data also suggest the type of bonding holding b-particles together in a-particles. SEC characterisation of liver glycogen at various time points in a day/night cycle indicates that liver glycogen is initially synthesised as b-particles, and then joined by an unknown process to form a-particles. These a-particles are more resistant to degradation, presumably because of their lower surface area-to-volume ratio. These findings have important implications for new drug targets for diabetes management.

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Section: Glycogen Size Characterisationmentioning

confidence: 90%

The Molecular Size Distribution of Glycogen and its Relevance to Diabetes

Gilbert

Sullivan

2014

Aust. J. Chem.

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“…Combining eq. (3) with the generalized universal calibration curve 9 we obtain an expression for M n,i :…”

Section: Methods Of Determining Local Polydispersitymentioning

confidence: 99%

Local polydispersity detection in size exclusion chromatography: Method assessment

Balke¹,

Mourey²

2001

J of Applied Polymer Sci

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Local polydispersity is the term describing the variety of molecules present at the same retention volume in size exclusion chromatography (SEC) analysis. In the analysis of a linear homopolymer, local polydispersity is generally attributed to the effect of axial dispersion: it can cause molecular size variety (i.e., imperfect resolution) at each retention volume and thus local polydispersity in the molecular weight. In the analysis of polymer blends (copolymers and branched polymers), it is possible to have local polydispersity, even when the resolution is perfect, because molecules of different compositions (or degrees of branching) can have the same molecular size in solution. Conventional SEC interpretation assumes no local polydispersity if the axial dispersion effects are negligible. Three methods are currently available for detecting local polydispersity by using a combination of differential refractive index, light scattering, and viscometer detectors: the chromatogram comparison method, the conventional calibration curve comparison method, and the universal calibration comparison method. Here we experimentally assess these three methods using polymer blends and emphasize the chromatogram comparison method. All three are shown to be useful for assessing triple detector systems, but they are capable of detecting local polydispersity due to molecular heterogeneity only for very large differences in specific refractive index increments in the blend components.

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“…Goldwasser's derivation is related to the previous one from Hamielec, who explained why ''conventional'' viscometry leads to a local number average molecular weight at each elution volume or hydrodynamic volume: [5,34,39] M n (V h ). Light scattering yields M w (V h ).…”

Section: Is the Weight Distribution Of Molecular Weights M And Hydrodmentioning

confidence: 98%

Viscosimetric detection in size‐exclusion chromatography (SEC/GPC): The Goldwasser method and beyond

Castignolles

Gaborieau

2010

J of Separation Science

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Size-exclusion chromatography (SEC or GPC) is the most widely used separation method to characterize polymers. The high level of complexity of most polymeric materials necessitates the use of not only concentration-sensitive detection but also structure-sensitive detection. Viscometry is usually used in conjunction with a concentration-sensitive detector and universal calibration to determine molecular weights of polymers. Goldwasser proposed to use a viscometer as a single detector to determine number-average molecular weights, M(n) (ACS Symposium Series, 521, 143). The method is particularly of interest when concentration-sensitive detection is not available, because the sample is isorefractive or not UV-absorbing, or because composition is not constant (copolymers). It has known very little applications so far. It actually does not only allow determining M(n), but also the number hydrodynamic volume distribution. This opens a wider range of applications for the Goldwasser method. Size-exclusion chromatography only yields inaccurate molecular weight distributions for some complex branched polymers. Hydrodynamic volume distributions have then a strong potential for comparative studies owing to their far higher accuracy. Our experimental tests highlight the fact that the method is highly sensitive to noise and careful optimization of the injection concentration is needed, but number distribution can be obtained as well as M(n).

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Generalized Universal Molecular Weight Calibration Parameter in GPC

Cited by 115 publications

References 7 publications

The Molecular Size Distribution of Glycogen and its Relevance to Diabetes

The Molecular Size Distribution of Glycogen and its Relevance to Diabetes

Local polydispersity detection in size exclusion chromatography: Method assessment

Viscosimetric detection in size‐exclusion chromatography (SEC/GPC): The Goldwasser method and beyond

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