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DISPEL

Summary:
A new NMR experiment (Destruction of Interfering Satellites by Perfect Echo Low-pass filtration, DISPEL) is introduced that facilitates the analysis of low-level components in high dynamic range mixtures by suppressing one-bond 13C satellite signals in 1H spectra. Since the natural abundance of 13C is around 1.1%, these satellites appear at 0.54% of the intensity of a parent peak, mimicking and often masking impurity signals. The new experiment suppresses one-bond
13C satellite signals, with high efficiency, at negligible cost in signal-to-noise ratio, and over a wide range of one-bond
coupling constants, without the need for broadband 13C decoupling.

Pulse sequence diagram:
The new method is an extension of the 1JCH low-pass filter, used for example in the HMBC in which a 90° 13C pulse is used to convert 1H coherence that is antiphase with respect to 13C into unobservable multiplet quantum coherence. The presence of 1H−1H scalar coupling means that this basic low-pass filter causes the phases of multiplet components to diverge, distorting and complicating phase-sensitive spectra. This J modulation can be refocused (for short times) by using a perfect echo instead of a simple spin echo. The perfect echo uses an orthogonal 90° pulse between two spin echoes to reverse the sense of J modulation.

Downloads:

Bruker
Pulse sequences:
dispel_2stage (right click and chose 'save ... as')
dispel_4stage (right click and chose 'save ... as')
dispel_4stage_pr (right click and chose 'save ... as')

Parameter Sets:
Raw data can be downloaded from the following DOI:
DOI: 10.17632/29y4xynz34.2

Reference:
P. Moutzouri, P. Kiraly, A. R. Phillips, S. R. Coombes, M. Nilsson and G. A. Morris, Anal. Chem., 2017, 89, 11898-11901.
DOI: 10.1021/acs.analchem.7b03787