Spectrus: Handling overlapping multiplets in crowded regions of NMR spectrum

Description
In crowded spectral regions, multiple multiplets can overlap, making it difficult to assign peaks and obtain accurate integrals. Spectrus provides tools to zoom, deconvolute, and manually define integration regions for such cases.

Solution

1. Load the NMR spectrum in Spectrus and locate the crowded region.
2. Zoom in on the region of interest to separate multiplets visually as much as possible.
3. Use peak picking:
   • Run automatic peak picking, then manually add or remove peaks where the algorithm missed or over‑picked.
4. For integration:
   • Define narrower integral regions around individual multiplets if they can be separated.
   • If overlapping is severe, consider integrating a combined region and using known proton counts to apportion contributions.
5. Right-click the multiplet and select Edit Multiplet to change J coupling constants, multiplicity, and to create overlapping multiplets.
6. For assignments:
   • Use additional 2D NMR data (e.g., COSY, HSQC, HMBC) where available to support assignments in crowded areas.
   • Mark uncertain assignments clearly in annotations or comments.
7. If needed, acquire higher‑field or additional experiments to reduce overlap and confirm assignments.