SEDFIT-MSTAR: molecular weight and molecular weight distribution analysis of polymers by sedimentation equilibrium in the ultracentrifuge

Sedimentation equilibrium (analytical ultracentrifugation) is one of the most inherently suitable methods for the determination of average molecular weights and molecular weight distributions of polymers, because of its absolute basis (no conformation assumptions) and inherent fractionation ability...

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Bibliographic Details
Published in:Analyst (London) 2014-01, Vol.139 (1), p.79-92
Main Authors: Schuck, Peter, Gillis, Richard B, Besong, Tabot M. D, Almutairi, Fahad, Adams, Gary G, Rowe, Arthur J, Harding, Stephen E
Format: Article
Language:English
Subjects:
Animals
Fractionation, Field Flow - methods
Humans
Instrumentation
Mathematical analysis
Mice
Molecular Weight
Molecular weight distribution
Polymers
Polymers - analysis
Polymers - chemistry
Pullulan
Sedimentation
Ultracentrifugation - methods
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Summary:Sedimentation equilibrium (analytical ultracentrifugation) is one of the most inherently suitable methods for the determination of average molecular weights and molecular weight distributions of polymers, because of its absolute basis (no conformation assumptions) and inherent fractionation ability (without the need for columns or membranes and associated assumptions over inertness). With modern instrumentation it is also possible to run up to 21 samples simultaneously in a single run. Its application has been severely hampered because of difficulties in terms of baseline determination (incorporating estimation of the concentration at the air/solution meniscus) and complexity of the analysis procedures. We describe a new method for baseline determination based on a smart-smoothing principle and built into the highly popular platform SEDFIT for the analysis of the sedimentation behavior of natural and synthetic polymer materials. The SEDFIT-MSTAR procedure - which takes only a few minutes to perform - is tested with four synthetic data sets (including a significantly non-ideal system), a naturally occurring protein (human IgG1) and two naturally occurring carbohydrate polymers (pullulan and λ-carrageenan) in terms of (i) weight average molecular weight for the whole distribution of species in the sample (ii) the variation in "point" average molecular weight with local concentration in the ultracentrifuge cell and (iii) molecular weight distribution. A new adaptation of sedimentation equilibrium in the analytical ultracentrifuge provides a user-friendly method for the analysis of molecular weights of polymers.
ISSN:0003-2654
1364-5528
DOI:10.1039/c3an01507f