Advanced solvent signal suppression for the acquisition of 1D and 2D NMR spectra of Scotch Whisky

A simple and robust solvent suppression technique that enables acquisition of high quality 1D 1H NMR spectra of alcoholic beverages on cryoprobe instruments was developed and applied to acquire NMR spectra of Scotch Whisky. The method uses three channels to suppress signals of water and ethanol, including those of 13C satellites of ethanol. It is executed in automation allowing high throughput investigations of alcoholic beverages. Based on the well-established 1D NOESY solvent suppression technique, this method suppresses the solvent at the beginning of the pulse sequence, producing pure phase signals minimally affected by the relaxation. The developed solvent suppression procedure was integrated into several homo- and heterocorrelated 2D NMR experiments, including 2D COSY, 2D TOCSY, 2D band-selective TOCSY, 2D J-resolved spectroscopy, 2D 1H, 13C HSQC, 2D 1H, 13C HSQC-TOCSY and 2D 1H, 13C HMBC. A 1D chemical-shift-selective TOCSY experiments was also modified. The wealth of information obtained by these experiments will assist in NMR structure elucidation of Scotch Whisky congeners and generally the composition of alcoholic beverages at the molecular level.