The nondestructive analysis of complex mixtures is an important challenge in analytical chemistry. In NMR spectroscopy, a useful tool for mixture analysis is DOSY (diffusion-ordered spectroscopy), which separates the signals from species of different sizes by exploiting their different diffusion behavior.

DOSY works well when separate signals are seen in the NMR spectrum. However, in proton NMR, this is only the case for the simplest of mixtures, because J coupling gives rise to multiplet structures. The recent introduction of so-called pure shift NMR methods (Pure Shift Yielded by Chirp Excitation (PSYCHE)), which collapse this multiplet structure by suppressing the effects of homonuclear coupling, has brought a great improvement in the resolution of proton NMR.

Matthias Nilsson, University of Manchester, UK, and colleagues have designed a PSYCHE-iDOSY NMR experiment, integrating DOSY into the PSYCHE method for pure shift NMR [1, 2]. The method gives some of the highest resolution proton DOSY spectra to date. Its sensitivity is an order of magnitude higher than previous pure shift DOSY experiments. According to the researchers, PSYCHE-iDOSY has the potential to find application in many different areas of chemistry where the spectra of complex mixtures need disentangling.

• Ultrahigh-Resolution Diffusion-Ordered Spectroscopy,
  Mohammadali Foroozandeh, Laura Castañar, Lucas G. Martins, Davy Sinnaeve, Guilherme Dal Poggetto, Claudio F. Tormena, Ralph W. Adams, Gareth A. Morris, Mathias Nilsson,
  Angew. Chem. Int. Ed. 2016.
  DOI: 10.1002/anie.201609676

References

• [1] Ultrahigh-Resolution NMR Spectroscopy,
  Mohammadali Foroozandeh, Ralph W. Adams, Nicola J. Meharry, Damien Jeannerat, Mathias Nilsson, Gareth A. Morris,
  Angew. Chem. Int. Ed. 2014, 53, 6990–6992.
  DOI: 10.1002/anie.201404111
• [2] Ultrahigh-Resolution Total Correlation NMR Spectroscopy,
  Mohammadali Foroozandeh, Ralph W. Adams, Mathias Nilsson, Gareth A. Morris,
  J. Am. Chem. Soc. 2014, 136, 11867–11869.
  DOI: 10.1021/ja507201t