Spectrus: Handling NMR spectra with low signal‑to‑noise ratio

Description
Low S/N spectra can make peak picking and integration difficult. Spectrus includes tools (smoothing, zero‑filling, appropriate apodization) to improve the appearance and extract usable information from noisy data.

Solution

1. Load the FID if available (not just the processed spectrum).
2. Under Process > Interactive Fourier Transform:
   • Apply a suitable apodization function (e.g., small exponential line broadening) by clicking Window Function and selecting User. Choose which apodization function parameters to use (e.g., select EM to apply exponential multiplication). Enter a Line Broadening (LM) parameter to increase the width of the transformed FT spectrum. This function is used to enhance S/N.
   • Consider specifying zero‑filling settings to increase resolution. The initial value displays the number of points in the current FID spectrum, while the final value displays the number of points that will be used by the Fourier Transform.
3. Transform and phase the spectrum carefully.
4. Apply mild smoothing if the display is still very noisy, ensuring peaks are not distorted.
5. Use more conservative peak picking thresholds to avoid detecting noise spikes as peaks.
6. Where possible, improve data quality at the instrument:
   • Increase the number of scans.
   • Optimize shimming and sample concentration.
7. Treat quantitative conclusions from very low S/N data with caution and document limitations.