Spectrus: Using NMR spectral overlays with historical lots to verify Sample Identity

Description
Re‑manufactured or reformulated materials can be verified by overlaying their NMR spectra with historical reference lots. Spectrus simplifies this overlay and comparison.

Solution

1. Import the NMR spectrum of the new lot and one or more historical reference spectra into the same Spectrus project.
2. Ensure consistent referencing (TMS or solvent) across all spectra.
3. Overlay the 1H spectra:
   • Select multiple NMR spectra by holding shift and left-clicking. Right-click on the selected spectra and select Overlay Selected Spectra. Align them in ppm and adjust vertical scaling so main peaks are comparable.
4. Check:
   • Peak positions and shapes.
   • Presence/absence of any extra peaks or impurities in the new lot.
5. If deviations are minor and consistent with acceptable variation (e.g., slight solvent content differences), document them.
6. For large differences or new peaks:
   • Investigate synthesis/processing changes.
   • Consider additional characterization (LC/MS, orthogonal techniques).
7. Archive overlay images and comments as evidence of lot comparability.