NMR chemical shifts of common laboratory solvents as trace impurities

The article examines the NMR chemical shifts of common laboratory solvents as trace impurities. Any potential hydrogenbond acceptor will tend to shift the water signal downfield. This is particularly true for nonpolar solvents. In contrast, in DMSO the water is already strongly hydrogen-bonded to the solvent, and solutes have only a negligible effect on its chemical shift. For D ₂O solutions there is no accepted reference for carbon chemical shifts. Researchers suggest the addition of a drop of methanol, and the position of its signal to be defined as 49.50 ppm; on this basis, the entries were recorded. The chemical shifts thus obtained are, on the whole, very similar to those for the other solvents. Alternatively, researchers suggest the use of dioxane when the methanol peak is expected to fall in a crowded area of the spectrum.