A nonlinear regression method for the analysis of 1H T2 dispersion curves including comments on the role of polydispersity
✍ Scribed by M. A. K. Williams; R. D. Keenan; T. K. Halstead
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 344 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
A nonlinear regression method is described in detail for analysing 1H (CarrÈPurcellÈMeiboomÈ T 2 Gill) dispersion curve measurements obtained from water-rich systems containing molecules possessing labile protons. The method is routine, provides well speciÐed error statistics and does not make assumptions about the accessibility or mobility of the guest molecule site. The approach is validated using data simulated with the CarverÈ Richards two-site exchange model and experimental measurements carried out on a series of methanol-d 4 Èwater mixtures of varying pH. Further simulations are described which investigate the role of polydispersity in determining the form of the dispersion curve and the relevance of the parameters extracted by Ðtting a composite curve to a single CarverÈRichards function. The procedure is subsequently used to Ðt experimental dispersion curves originating from maltodextrinÈwater systems and the interpretation of the results is shown to be consistent with previously suggested ideas for molecular interactions in polysaccharide systems, involving discrete units of double helical nature, which can further aggregate to develop structure at a supramolecular level.