Spectrus: Distinguishing dynamic exchange from impurity peaks in NMR spectra

Description
Additional or broadened peaks in NMR spectra may arise from dynamic exchange (e.g., conformers, rotamers, proton exchange) rather than discrete impurities. Correctly distinguishing these cases is important for interpretation.

Solution

1. Inspect the NMR spectrum in Spectrus:
   • Note extra peaks, broad shoulders, or temperature‑dependent changes.
2. Consider dynamic exchange indicators:
   • Peaks that broaden, merge, or split as temperature changes.
   • Exchangeable protons (OH, NH) showing variable intensity.
3. If possible, acquire additional spectra:
   • At different temperatures (VT NMR).
   • With and without D₂O shake (for exchangeable protons).
4. In Spectrus, compare spectra:
   • Use stacked plots to see how suspected peaks behave with temperature or D₂O.
5. If peaks disappear or coalesce with temperature/D₂O:
   • Treat them as arising from dynamic processes rather than discrete impurities.
6. Document your conclusion in the record, indicating which signals are attributed to dynamic exchange vs true sample impurities.