Manchester NMR Methodology Group

Summary:
Pure Shift Relaxation Encoded Selective TOCSY (PUREST) builds on the REST family of NMR experiments for mixture analysis allowing for the extraction of component subspectra from mixtures. It uses isotropic mixing to label whole spin systems with the relaxation times (e.g. T₁, T₂) of individual spins. Followed by a PSYCHE J refocussing element to remove the effects of homonuclear scalar coupling, (J_HH), on the spectra.

Pulse sequence:
The basic structure of the pulse sequence consists of an initial generation of T₁ or T₂ relaxation-weighted single quantum coherence (either using the inversion recovery or PROJECT sequence, respectively); a selective 180^o pulse to select signals at a single chemical shift; an isotropic mixing sequence (here DIPSI-2 with zero-quantum coherence suppression) to transfer coherence throughout each spin system; and a final PSYCHE J refocusing element to remove the effects of homonuclear scalar coupling on the spectra.

Downloads:
Bruker pulse programs::
PUREST₁
PUREST₂

Experimental data can be downloaded from
here.

Processing:
The processing of PUREST₁ and PUREST₂ experimental data is straightforward using the free and open source software package GNAT.

Reference:
Giving Pure Shift NMR Spectroscopy a REST ─ Ultrahigh-Resolution Mixture Analysis, M. Smith, L. Castañar, R. W. Adams, G. A. Morris, M. Nilsson. Analytical Chemistry, 2022, 94, 12757-12761. DOI: 10.1021/acs.analchem.2c02411

Please note that copyright restrictions prevent us from placing the pdf files on our website, however, this article is open access and the pdf can be downloaded from ACS website.