NMR Reference Offset

Re-reference NMR chemical shifts to observed TMS zero.

Description

Chemical-shift referencing applies a constant offset so a measured TMS reference is placed at zero ppm.

Chemical-shift referencing applies a constant offset so a measured TMS reference is placed at zero ppm. Every supplied shift receives the same translation.^[1]

Re-reference NMR chemical shifts to observed TMS zero.

When to use NMR Reference Offset

Use this tool to re-reference NMR chemical shifts to observed TMS zero.

Prepare the measured profile, formula counts, upstream model outputs or caller-defined reference criteria requested. Keep paired entries aligned and units, sample basis and preprocessing consistent.

How to use NMR Reference Offset and understand its results

Prepare the measured profile, formula counts, upstream model outputs or caller-defined reference criteria requested. Keep paired entries aligned and units, sample basis and preprocessing consistent.
Enter observedTmsPpm, measuredShiftsPpm using the field table and calculation rules, then run the tool.
Read referenceOffsetPpm, correctedShiftsPpm. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
observedTmsPpm	Observed tms ppm	number	Required
measuredShiftsPpm	Measured shifts ppm	list of number	Required

Enter finite observed reference and shift list, which may be empty. Return the offset and shifted values in input order.

offset=−observedTMSppm; corrected_i=shift_i+offset

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
referenceOffsetPpm	Reference offset ppm	number
correctedShiftsPpm	Corrected shifts ppm	list of number

json

{
  "input": {
    "observedTmsPpm": 0.2,
    "measuredShiftsPpm": [
      1.2,
      2.2
    ]
  },
  "output": {
    "referenceOffsetPpm": -0.2,
    "correctedShiftsPpm": [
      1,
      2
    ]
  }
}

Limitations and assumptions

No peak detection, reference identity check or frequency-dependent calibration is performed.

Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Lists are limited to 100,000 entries; the rules above may require smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use NMR Coupling From PPM: Convert NMR peak separation in ppm to J-coupling hertz at a field frequency. For a complementary task, use NMR Bucket Integrals: Bin NMR spectral integrals by configurable chemical-shift width.

References

NMR Reference Offset — tool.io

Similar or alternative tools

NMR Coupling From PPM
Convert NMR peak separation in ppm to J-coupling hertz at a field frequency.
NMR Bucket Integrals
Bin NMR spectral integrals by configurable chemical-shift width.