Spectrus: Using an internal standard for quantitative NMR (qNMR)

Description
Quantitative NMR (qNMR) requires an internal standard with known purity and concentration. Spectrus can use integrals of the analyte and standard peaks to calculate analyte concentration.

Solution

1. Prepare the sample with a suitable internal standard:
   • Known concentration and purity.
   • Non‑overlapping peaks with analyte signals.
2. Acquire the NMR spectrum under quantitative conditions (sufficient relaxation delay, appropriate pulse angle).
3. In Spectrus:
   • Correct phase and baseline.
   • Integrate the internal standard peak(s) and analyte peak(s).
4. Use Tools > qNMR or if available, add the concentration_calculation.pas and strength_calculation.fsbin macro files to the Macro Organizer. Use these macros to run the qNMR script.
5. Enter standard information:
   • Concentration, purity, and number of protons represented by the standard signal.
6. Use qNMR calculation tools (if available) or manually compute:
   • Analyte amount from ratio of integrals, correcting for proton count and standard details.
7. Report the calculated concentration or purity of the analyte, including details of the standard and acquisition parameters.