Quantitative 2D HSQC NMR determination of polymer structures by selecting suitable internal standard references
2007 (English)In: Magnetic Resonance in Chemistry, ISSN 0749-1581, E-ISSN 1097-458X, Vol. 45, no 1, 37-45 p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2007. Vol. 45, no 1, 37-45 p.
NMR, HSQC, quantification, polymers, transverse relaxation (T-2), internal standards, resonance offset, dept pulse sequence, c-13 nmr, adiabatic pulses, spectroscopy, lignin, sensitivity, dependence, aggregation, improvement, inversion
IdentifiersURN: urn:nbn:se:kth:diva-16317DOI: 10.1002/mrc.1914ISI: 000243349900005ScopusID: 2-s2.0-33845921628OAI: oai:DiVA.org:kth-16317DiVA: diva2:334359
QC 201005252010-08-052010-08-05Bibliographically approved