Quantitative 2D HSQC NMR determination of polymer structures by selecting suitable internal standard references
✍ Scribed by Liming Zhang; Göran Gellerstedt
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 467 KB
- Volume
- 45
- Category
- Article
- ISSN
- 0749-1581
- DOI
- 10.1002/mrc.1914
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
A new analytical method based on the 2D HSQC NMR sequence is presented, which can be applied for quantitative structural determination of complicated polymers. The influence of T~1~ and T~2~ relaxations, off‐resonance effects, coupling constants and homonuclear couplings are discussed. It was found that the T~2~ values measured on polymeric samples with the conventional HSQC‐CPMG sequence could not be used to correct the errors caused by T~2~ relaxations during the polarization transfer delay. A unique way of selecting the proper internal standard reference signal(s) is therefore proposed to eliminate the major errors caused by T~2~ relaxations, resonance offsets, coupling constant deviations and homonuclear couplings. Two polymer samples, a cellulose triacetate and an acetylated lignin, have been used to illustrate the principles. The methodology developed in this work is robust to instrument miss‐setting and it can find wide‐spread applications in areas where a quantitative analysis of structurally complicated polymers is necessary. Copyright © 2006 John Wiley & Sons, Ltd.