NMRStructureQualityChecker

NMR Structure Quality Checker — Control of NMR Spectrum Quality

ℹ️  Utility checks critical parameters of Nuclear Magnetic Resonance spectra quality (USP <761> / Ph. Eur. 2.2.33):
   • Signal-to-Noise Ratio (S/N): ≥150:1 (for quantitative analysis)
   • Resolution: ≤0.55 Hz (at half height)
   • Linewidth: ≤1.0 Hz (at 0.55% height, shimming indicator)
   • Shift Calibration: standard deviation ≤0.01 ppm

⚠️  CRITICAL: Poor shimming (broad peaks) makes multiplet separation and accurate integration impossible!
   Low S/N hides minor impurities or spin-spin coupling.

Usage:
 NMRStructureQualityChecker.exe                            → demo mode (console output)
 NMRStructureQualityChecker.exe input.csv output.json      → evaluate your data

Input format:
BatchNumber,SignalToNoiseRatio,ResolutionHz,Linewidth055Hz,ReferenceShiftDeviation,PhaseCorrectionScore

Example:
 NMR-STR-2026-001,250.0,0.45,0.8,0.002,98.0

— WHY IS THIS NEEDED?
NMR is the most informative method for confirming structure of organic molecules and APIs.
• Spectrum quality directly affects reliability of structure elucidation and quantitative calculations (qNMR).
• Resolution and linewidth parameters reflect magnetic field homogeneity (shimming quality).
• S/N determines impurity detection limit and signal integration reliability.
• Automation of QC parameter check allows operator to immediately re-acquire spectrum if poor, saving time.

⚠️  CRITICAL:
• Shimming must be optimized before each measurement.
• Sample temperature must stabilize before acquisition.
• Sample concentration must be sufficient for good S/N without detector saturation.
• Solvent must be high-quality deuterated.

Key features:
• Assessment of spectrum suitability for structural identification.
• Control of instrument technical parameters (magnet, probe).
• Support for Bruker, Jeol, Agilent spectrometer data.

Critical parameters:
• S/N Ratio: >= 150
• Resolution: <= 0.55 Hz
• Linewidth (0.55%): <= 1.0 Hz
• Reference Shift: <= 0.01 ppm

💡 Usage tips:
1. Use standard sample (e.g., ethylbenzene in CDCl3) for daily resolution and sensitivity check.
2. Monitor cryogen levels (liquid nitrogen/helium) in magnet.
3. Avoid paramagnetic impurities (oxygen, metals) which broaden peaks.
4. For quantitative NMR (qNMR), use sufficient relaxation delay (D1 >= 5*T1).
5. Check phase and baseline correction before integration.

⚠️ Note: NMR requires high stability of external conditions. Vibrations and temperature fluctuations in the lab can significantly degrade spectrum resolution.