qNMR Quantification

qNMR Quantification documents how MolTrace turns integrated NMR evidence into quantitative outputs that can be reviewed, approved, and exported.

Outline

• Select internal or external reference strategy.
• Review integration regions and excluded peaks.
• Confirm concentration, purity, and uncertainty outputs.
• Attach the quantitative result to a report.
• Preserve the source FID archive and review decisions in the audit trail.

Quantitative region integration

The moltrace.spectroscopy.integration module exposes three production integration methods behind a single dispatcher and a typed endpoint. All three operate on a processed spectrum and a set of classified peaks plus one or more user-defined regions; each method returns, per region, the integral value, its normalised ratio, a confidence, and provenance indices back into the peak list.

Method	What it computes	When to use
Sum	Trapezoidal area over the window.	Clean, well-separated regions with no solvent or impurity overlap.
Edited Sum (default)	Trapezoidal area with a proportional-by-height subtraction of overlapping solvent and impurity peaks.	The default for reviewer workflows — robust to typical residual solvent and impurity contamination.
Peaks	The sum of the fitted compound peak areas inside the region.	Crowded regions where peak fitting from the GSD pipeline is more trustworthy than baseline-bounded trapezoidal area.

Reference accuracy

On synthetic spectra with known impurity area fractions of 5 % / 10 % / 25 %, Edited Sum recovers the true compound integral within 1 %. This is the headline accuracy claim qNMR reviewers can rely on for routine impurity-aware integration.

Endpoint surface

POST /spectrum/analyze/integration carries the spectrum arrays, classified peaks, one or more regions, and a method selector. The response carries one entry per region with value, ratio, confidence, and the source-peak indices that contributed. Each call emits a spectrum.analyze_integration audit event so quantitative reviews remain reconstructible end-to-end. (v0.7.7, 2026-05-31)

qNMR purity — internal standard & PULCON

Beyond region integration, moltrace.spectroscopy.qnmr turns a resonance integral into a mass-fraction purity by the two standard, non-proprietary qNMR methods, with full provenance and GUM-propagated uncertainties.

• Internal-standard purity — calculate_purity_internal_standard(...) applies P_x = (I_x/I_std)·(N_std/N_x)·(M_x/M_std)·(m_std/m_x)·P_std against a weighed internal standard.
• PULCON (external standard) — calculate_purity_pulcon(...) uses the reciprocity principle (signal per spin proportional to 1 / 90°-pulse-width) with documented temperature, receiver-gain, and scan corrections that default to matched conditions.
• Integration-fitness ranking — rank_multiplets_for_qnmr(...) scores each candidate analyte multiplet on a transparent additive scale (max 13): no solvent / impurity in the window (+5), clean baseline (+3), narrow lines FWHM ≤ 5 Hz (+2), determinate multiplicity (+2), not exchange-broadened (+1) — so reviewers integrate the most trustworthy resonance.
• Auditable result — both methods return a frozen PurityResult (purity %, uncertainty %, method, and every intermediate ratio) with the combined standard uncertainty by GUM quadrature, so a purity number is reconstructible end-to-end. Closed-loop synthetic recovery is < 0.5 % absolute (the SDBS acceptance target). (v0.8.3, 2026-06-05)