Analysis of the Phases of Signals in Two-Dimensional NMR

2017 - Volume 6 eMagRes
Volume 6, Issue 1
Damien Jeannerat

Damien Jeannerat

University of Geneva, Geneva, Switzerland

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First published: 19 March 2017
Citations: 2

Abstract

Some two-dimensional experiments suffer from ‘phase problems’, meaning that instead of resulting with spectra with absorptive signals, they have a dispersive component causing extensive line broadening and baseline distortions. We shall illustrate how a spectral decomposition determining the phases of the peaks together with the other lineshape parameters makes it possible to reconstruct synthetic spectra containing signals with corrected phases. When applied to the two-pulse COSY spectra, this type of analysis allows one to discriminate the diagonal and the cross peaks according to their phases and reconstruct separate synthetic spectra with pure absorption lineshapes. Similarly, J-resolved spectra producing phase-twisted signals can be analyzed and have their phases corrected. This method can also exploit spectra generated by NMR pulse sequences encoding an NMR parameter as a controlled phase distortion in F1 dimension. In the case of chemical shift encoding, the extracted information were used to resolve the ambiguities caused by spectral aliasing. Finally it can be used to identify and eliminate signal artifacts when their phase properties differ from those of normal signals.

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