Jaconir
Jaconir NMR Lab

NMR Peak
Assignment Assistant

Assign proton NMR peaks to atoms using chemical shifts, multiplicity and interactive visualization.

MoleculeSpectrumPeak selectedAtom highlightsAssignment

Workspace

Paste peaks — assign with evidence. You stay in control.

How to assign

  1. 1Paste
  2. 2Peak
  3. 3Atom
  4. 4Assign

1 · Paste peaks

Paste your peak list on the left to start.

Assigned

0

Remaining

0

Unknown

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Progress

0%

Detected peaks

No peaks imported yet.

ShiftMultStatusAssignmentConf

No peaks imported

Paste a peak list on the left to populate this table.

Interactive spectrum

Waiting for peak list

Spectrum disabled

Paste a peak list to draw the interactive spectrum.

No molecule available

Select a peak first, then choose a molecule preset on the left.

Assignment details

No assignment yet

Import peaks, then select a peak to open assignment controls.

Learn & understand

Evidence-first peak assignment for ¹H NMR

What is peak assignment?

Assignment maps each observed resonance to a structural proton environment. It is a hypothesis supported by shift, multiplicity, integration, and consistency across the molecule.

How chemical shift helps

δ reports the electronic environment. Oxygen-, nitrogen-, and aromatic-adjacent protons appear downfield; remote alkyl groups appear upfield.

How multiplicity helps

Splitting encodes neighbouring equivalent protons (n+1). A quartet next to a triplet is classic for an ethyl group.

Integration

Relative integrals approximate proton counts. Use them to decide CH₃ vs CH₂ vs CH once impurities are removed.

Common assignment strategy

1) Mark solvent/impurity peaks. 2) Assign distinctive singlets. 3) Pair coupled multiplets. 4) Leave ambiguous peaks tentative.

Assignment workflow

Jaconir Lab path: impurity check → shift prediction → splitting literacy → assignment workspace. Evidence before labels.

Mistakes to avoid

Forcing every peak, ignoring multiplicity mismatches, assigning impurities as product, and overstating confidence without 2D NMR.

Continue your NMR workflow

A path from impurity check → prediction → assignment

  1. 1

    NMR Impurity Solver

    Completed

    Identify common solvent impurities before assigning compound peaks.

  2. 2

    NMR Chemical Shift Predictor

    Completed

    Predict unknown proton environments after removing solvent impurities.

  3. 3

    NMR Splitting Pattern Simulator

    Completed

    Understand why peaks split into doublets, triplets and multiplets.

  4. 4

    Peak Assignment Assistant

    You are here

    Assign ¹H peaks to atoms with shift, multiplicity, and structure.

Related instruments

More free browser-based chemistry tools

Full library

NMR Impurity Solver

Identify solvent impurity peaks from Fulmer-table shifts.

NMR Chemical Shift Predictor

Estimate expected ¹H δ from molecular environment.

NMR Splitting Pattern Simulator

Visualize n+1 splitting, Pascal intensities, and J-coupling.

Electron Configuration Viewer

Orbital diagrams and quantum numbers for all 118 elements.

Frequently asked questions

How accurate is this tool?

It does not claim structural proof. Environment hints are teaching-range heuristics from chemical shift and multiplicity. You remain responsible for the final assignment.

Does it replace professional software?

No. It is an assignment workspace for education and early analysis — not a replacement for MestReNova, TopSpin, or full 2D elucidation suites.

Can I upload a spectrum?

Not as a FID/JCAMP file. Paste a peak list (shift + multiplicity). The SVG spectrum is rebuilt from those peaks for interaction.

Can I assign manually?

Yes. Every assignment is manual or user-confirmed. Suggestions never auto-write an assignment without your action.

Why are some assignments tentative?

Use tentative when shift/multiplicity fit more than one environment, or when you lack integration / 2D confirmation. Tentative is scientifically honest.

How should assignments be verified?

Cross-check with predicted shifts, splitting logic, integrals, impurity tables, and — for research — COSY/HSQC/HMBC when needed.

Is this AI?

No. Parsing and suggestions are deterministic rules running entirely in your browser. No models, no network calls for assignment.

Do I need a molecular structure?

Optional. You can type atom labels freely. Preset SVGs help visualization; SMILES is stored for your notes/report only.

Continue · Structure Elucidation
Open Chemistry Lab
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