Acceleration of 3D DOSY NMR by Spatial Encoding of the Chemical Shift

Diffusion-ordered NMR spectroscopy (DOSY) is a powerful method for the analysis of solution mixtures. With 3D DOSY, the 2D NMR spectra of a mixture's components can be separated according to the translational diffusion coefficient of each component. The acquisition of 3D DOSY data is, however, very time-consuming because of the need to consecutively acquire scans for both the diffusion and the indirect spectral dimensions. We show that spatial encoding of the indirect spectral dimension, of the kind used in ultrafast 2D NMR, can accelerate 3D DOSY experiments by an order of magnitude or more. This is illustrated with homonuclear single-quantum (COSY) and double-quantum (DQS) correlation spectra. Implementations with concatenated and incorporated (iDOSY) diffusion blocks are compared and in both cases, 2D spectra are separated with less than 6 min of experiment time.