HiFSA

HiFSA (¹H iterative Full Spin Analysis) is a quantum-mechanical approach to interpreting ¹H NMR spectra. Instead of reading off peak positions and apparent splittings by eye, HiFSA builds a spin-system model of the molecule and iteratively adjusts its chemical shifts (δ), coupling constants (J), line shapes and populations until the simulated spectrum matches the experimental one.

The result is a complete, reproducible "fingerprint" of the spectrum that:

• Captures every chemical shift and coupling constant, including those hidden in higher-order multiplets and overlapping signals.
• Can be re-simulated at any field strength, making it independent of the spectrometer frequency used for acquisition.
• Supports structure verification, identity testing and purity/quantitative (qHNMR) analysis, because the fit quality can be measured objectively.

Producing a HiFSA analysis

HiFSA analyses are typically performed in Cosmic Truth (CT) by NMR Solutions. A typical workflow is:

1. Load the experimental ¹H spectrum (FID) and the structure of the compound (e.g. an SDF/MOL file).
2. Let Cosmic Truth build the spin systems for the solute and solvent(s).
3. Iterate the quantum-mechanical fit until the simulated and experimental spectra agree.
4. Export the results. nmrXiv understands the following exports:
   • The analysis report as a PDF.
   • The analysis export as a zip archive whose name ends in _export.zip. It contains the Cosmic Truth analysis CSV (with ANALYSIS INFO and SCORES sections) and, optionally, reference CSVs (*_REF.csv) and per-spin-system CSVs under EXTRA/.
   • A .blob analysis file, if your export includes one.

Fit scores

Cosmic Truth summarises the quality of a HiFSA fit with five scores: Match, RMS, Shift similarity, Coupling similarity and Intensity. nmrXiv displays these values as reported by Cosmic Truth; refer to the Cosmic Truth documentation for their exact definitions.

Submitting HiFSA results to nmrXiv

HiFSA results are submitted alongside the raw data of the sample they belong to. No extra option has to be selected during upload: nmrXiv detects HiFSA folders automatically based on how the files are organised.

Folder structure

Put all HiFSA files in their own folder, and place that folder inside the sample (study) folder or next to the folder that holds the raw data. The two layouts below are both recognised:

Compound/                 ← study (sample)
├── 1/                    ← Bruker dataset (acqus, acqu, pdata)
├── 2/                    ← Bruker dataset
└── hifsa/                ← HiFSA folder
    ├── report.pdf
    ├── compound_export.zip
    └── compound.blob

Compound/
├── raw/                  ← study (contains the raw datasets)
│   ├── 1/
│   └── 2/
├── proc/                 ← processed data (ignored as a sample)
└── hifsa/                ← HiFSA folder, sibling of the study folder
    ├── report.pdf
    └── compound_export.zip

A folder is recognised as a HiFSA folder when either:

• it is named hifsa (upper or lower case), or
• it directly contains a .blob file.

Inside the HiFSA folder, nmrXiv looks for the following files at the top level of the folder:

File	Required	Used for
*.pdf	Optional	Previewing the HiFSA report. If there are several PDFs, the first one is used.
*_export.zip	Optional	Extracting the fit scores, spin systems, chemical shifts, couplings, line shapes and integration statistics.
*.blob	Optional	Detection only (it marks the folder as a HiFSA folder).

TIP

A HiFSA folder is not a sample and not a dataset. nmrXiv never creates a study or a spectrum from it. A HiFSA folder on its own (without raw data next to it) will therefore not produce a study. Always upload HiFSA results together with the raw spectra of the same sample.

WARNING

Do not name a folder that contains raw instrument data hifsa. HiFSA detection takes precedence over instrument detection, so the raw data in that folder would not be turned into a dataset.

Reviewing HiFSA results during submission

After the draft has been processed, open the sample in step 2 of the submission. Samples with HiFSA results show a collapsible HiFSA section below the spectra viewer:

• If an _export.zip with scores was found, nmrXiv shows:
  • A radar chart and summary cards of the five fit scores.
  • The analysis remarks, a link back to the analysis in Cosmic Truth, the solvent, the temperature and provenance information (who created/modified the analysis and when).
  • Collapsible tables for the spin systems (name, type, formula, molecular weight, InChIKey, population, LRMS), chemical shifts (δ in ppm, spin and nuclei count, line shape, LRMS), coupling constants (J in Hz), line shapes (line width and Gaussian fraction) and QMGI integration statistics. Shift, coupling, line-shape and QMGI rows are grouped by spin system.
• If only a PDF was found, the HiFSA report is shown inline in the browser.

If the solvent is not stated in the analysis CSV, nmrXiv falls back to the reference CSVs, then to the solvent spin systems (preferring a deuterated solvent over residual water), and finally to the analysis remarks (for example ... in DMSO-d6).

Troubleshooting

Symptom	Likely cause
No HiFSA section appears	The HiFSA folder is not named hifsa and has no .blob file, or it is not inside/next to the study folder (for example it is nested one level too deep, or placed under a different sample).
Only the PDF is shown, no scores	There is no file ending in _export.zip directly in the HiFSA folder, or the zip does not contain a CSV with ANALYSIS INFO / SCORES sections, or none of the five scores is present.
The folder with the HiFSA files became a separate study	The folder was not recognised as a HiFSA folder (not named hifsa, no .blob file) and also contained raw data that was detected as a dataset. Keep HiFSA exports and raw data in separate folders and name the HiFSA folder hifsa.