Hi Teresa,
Low-field instruments often provide better resolution than high-field
instruments, especially when the latter are not shimmed well enough. We
frequently see resolutions in 1D-1H spectra from low-field instrument of
around 0.5 Hz, whereas high-field instruments are usually worse by a
factor of two or even more. Since the amount of spectral information
(number of resolvable peaks) roughly depends on the sum of both, a
better resolution compensates for the lower dispersion at least to some
extent. Considering the 125MHz instrument available from Q Magnetics, a
twofold better resolution would compensate for the poorer dispersion to
achieve about the same information content as of a 250-300 MHz=
instrument, which is well enough to characterize most small molecules.
Of course, low-field spectra still show more second and higher order
effects, but these effects can have considerable diagnostic value that
can be taken advantage of by computational spectral analysis.
Cheers,
Matthias
info_at_nmrqualytics.com kirjoitti 8.9.2023 20:53:
> Hi all,
>
> I have a question regarding benchtop NMRs (80, 90, and 100 MHz). They
> seem very useful in classroom settings for teaching purposes as well
> as in chemical manufacturing settings for QA/QC purposes. How useful
> are the benchtops for R&D with small organic compounds? What's the
> resolution and sensitivity of a benchtop in comparison with 300 or 400
> MHz systems?
>
> Thank you,
>
> *Teresa Daubenspeck*
> Analytical Instrument Technology | Qualytics
> info_at_nmrqualytics.com | 267-935-9882
>
>
>
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