Practical aspects of real-time pure shift HSQC experiments

Pure shift NMR spectroscopy has become an efficient tool for improving
resolution in proton NMR spectra by removing the effect of homonuclear couplings. The introduction of real-time acquisition methods has allowed the main drawback of pure shift NMR, the long experiment times needed, to be circumvented. Real-time methods use periodic application of J-refocusing pulse sequence elements, acquiring a single free induction decay, in contrast to previous methods that construct a pure shift interferogram by concatenating excerpts from multiple free induction decays. In the important HSQC experiment, implementing real-time pure shift data acquisition typically leads to the simultaneous improvement of both resolution and sensitivity. The current limitations of and problems with real-time pure shift acquisition methods are
discussed here in the context of HSQC experiments. We aim to provide a detailed
account of the technical challenges, together with a practical guide to exploiting the full potential of such methods.