When acquiring pure shift 1H NMR experiments on a sample in common organic solvent (chloroform, acetone, toluene), very disappointing spectra can be obtained: low signal-to-noise ratio, phase distortion. Ironically, this is even worse for NMR spectrometers equipped with cryoprobes, designed to improve sensitivity. Signal losses in pure shift NMR are caused by convection in the NMR sample, which is often overlooked, but can be very troublesome in NMR experiments using field gradient pulses. For pure shift experiments, this work shows that a very simple adjustment of experimental parameters almost completely restores the lost signal. The principle is not confined to pure shift methods, and is likely to find application in many experiments involving pulsed field gradients; it will be particularly helpful in flow chemistry / reaction monitoring by NMR.
- Recovering sensitivity lost through convection in pure shift NMR
Elsa Caytan, Howard M. Foster, Laura Castañar, Ralph W. Adams, Mathias Nilsson and Gareth A. Morris *
Chem. Commun., 2023, 10.1039/d3cc04112c
- Elsa Caytan, Univ Rennes, ISCR-CNRS UMR 6226, F-35000 Rennes, France
elsa [dot] caytanuniv-rennes [dot] fr
Published November 6, 2023