Diffusion-ordered NMR spectroscopy (DOSY) is increasingly widely used for the analysis of mixtures by NMR spectroscopy, dispersing the signals of different species according to their diffusion coefficients. DOSY is used primarily to distinguish between the signals of different species, with the interpretation of the diffusion coefficients observed usually being purely qualitative, for example to deduce whether one species is bigger or smaller than another. In principle, the actual values of diffusion coefficient obtained carry important information about the sizes of different species and on interactions between species, but the relationship between diffusion coefficient and molecular mass is in general a very complex one. Here a recently proposed analytical relationship between diffusion coefficient and molecular mass for the restricted case of small organic molecules is tested against a wide range of data from the scientific literature and generalized to cover a range of solvents and temperatures.

The GNAT (General NMR Analysis Toolbox) is a free and open‐source software package for processing, visualising, and analysing NMR data. It supersedes the popular DOSY Toolbox, which has a narrower focus on diffusion NMR. Data import of most common formats from the major NMR platforms is supported, as well as a GNAT generic format. Key basic processing of NMR data (e.g., Fourier transformation, baseline correction, and phasing) is catered for within the program, as well as more advanced techniques (e.g., reference deconvolution and pure shift FID reconstruction). Analysis tools include DOSY and SCORE for diffusion data, ROSY T 1/T 2 estimation for relaxation data, and PARAFAC for multilinear analysis. The GNAT is written for the MATLAB® language and comes with a user‐friendly graphical user interface. The standard version is intended to run with a MATLAB installation, but completely free‐standing compiled versions for Windows, Mac, and Linux are also freely available.

Diffusion-ordered spectroscopy (DOSY) is an effective method for the analysis of intact mixtures, but the quality of results is critically limited by resolution in the NMR dimension. A new experiment integrating diffusion weighting into the PSYCHE method for pure shift NMR spectroscopy allows DOSY spectra to be measured with ultrahigh NMR resolution at improved sensitivity.

A new NMR experiment aids the identification of components in complex systems, including mixtures.

A new family of NMR experiments for mixture analysis (Relaxation-Encoded Selective TOCSY, REST) allows the extraction of component subspectra from mixtures. It uses isotropic mixing to label whole spin systems with the relaxation times (e.g. T, T) of individual spins.