Automated CORE, RECORD, and GRECORD processing of multi-component PGSE NMR diffusometry data

Pulsed gradient spin-echo (PGSE) NMR techniques have found growing and widespread use for investigation of a variety of physicochemical phenomena in solution, because of their effect on molecular self-diffusion, and for primarily analytical purposes, for example separation of overlapping NMR bandshapes obtained from multi-component samples. A multi-component spectral separation approach previously introduced by the author (named CORE) is founded on the fact that each part of a molecule diffuses at the same rate, and thus PGSE NMR signals from each functional group will attenuate in a fully concerted fashion throughout a PGSE experiment. Numerical separation and analysis of component NMR spectra by CORE processing is therefore stabilized and steered by this prior knowledge constraint. However, even with two components and with similar self-diffusion rates, numerical instability and cross-talk between similar component self-diffusion may appear even with good experimental signal-to-noise ratio and only minor or no component spectral overlap. So-called RECORD processing was recently introduced to accompany the CORE method. In this more robust variant, spectra are divided into several sub-regions that are treated separately and combined in a later stage. The rationale for and advantages of the generic RECORD-based approach are further discussed and illustrated. A further hybrid CORE processing variant named GRECORD is suggested and briefly tested.