Biexponential fitting of diffusion-ordered NMR data: practicalities and limitations.
High resolution diffusion-ordered NMR spectroscopy (HR-DOSY) generally uses monoexponential fitting of the diffusional attenuation of pulsed-field gradient stimulated echo spectra and can, thus, only give proper separation of signals in the diffusion domain where the individual peaks are well-resolved in the spectral domain. In principle, it should be possible to resolve the decays of coincident spectral peaks by multiexponential fitting, but the well-known fundamental difficulties in such a separation are exacerbated by instrumental distortions of the signal decay. The limitations imposed on biexponential fitting by finite signal-to-noise ratio and by the distortion of the theoretical form of the signal attenuation as a result of pulsed-field gradient nonuniformity are explored, and the improvement in DOSY spectra produced using biexponential fitting afforded by compensating for the latter are illustrated.
Nilsson
Mathias
M
School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK. mathias.nilsson@manchester.ac.uk
Connell
Mark A
MA
Davis
Adrian L
AL
Morris
Gareth A
GA
D000433:1-Propanol / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation / Q000379:methods* / Q000592:standards*; D000439:Pentanols / Q000032:analysis*; D012015:Reference Standards; D012680:Sensitivity and Specificity; D013395:Sucrose / Q000032:analysis*
D000439:Pentanols; D013395:Sucrose; D000433:1-Propanol; C029683:isopentyl alcohol