Cyanocobalamin. The corrinoid cyanocobalamin (Figure ), a synthetic vitamin B12, is used in cases of vitamin B12 deficiency anaemia, typically as an oral supplement. Pure shift NMR simplifies the spectrum, collapsing multiplets into singlets and improving resolution, but solvent suppression is required to avoid intense artefacts obscuring the pure shift spectrum. Figure compares spectra acquired using a 1 H pulse-acquire experiment (Figure ), NOESY-presaturation PSYCHE (Figure ), and the new PSYCHE-iWG (Figure ). Both PSYCHE-iWG and NOESY-presaturation PSYCHE offer good solvent signal suppression (2000-and 500-fold, respectively). Eliminating signal overlap facilitates discrimination between chemical environments and, coupled with 2D correlation methods, increases the ease of structure assignment (see Supporting Information, Table ).