Suppression of artefacts in nuclear overhauser effect difference spectroscopy by reference deconvolution

Reference deconvolution allows the effects of common instrumental imperfections in Fourier transform NMR, including field inhomogeneity, field/frequency ratio instability and pulse phase and amplitude irreproducibility, to be removed from spectra containing a well‐resolved reference signal. By applying reference deconvolution to the two component spectra, perturbed and unperturbed, of a nuclear Overhauser effect difference spectrum, the artefacts that instrumental imperfections normally cause in the difference spectrum may be suppressed. A small penalty in signal‐to‐noise ratio is paid for an improvement of several orders of magnitude in artefact suppression, allowing even very small Overhauser enhancements to be detected with confidence. Results are presented showing the reduction of difference artefacts for methyl singlets, normally the most severe test for NOE difference spectra, to below 1 part in 50 000.