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 Pure Appl. Chem., Vol. 69, No. 12, pp. 2489-2495, 1997.

PHYSICAL CHEMISTRY DIVISION

COMMISSION ON MOLECULAR STRUCTURE AND SPECTROSCOPY

Parameters and Symbols for Use in Nuclear Magnetic Resonance

(IUPAC Recommendations 1997)

A. NMR EXPERIMENTAL PARAMETERS for reporting in publications

1. Introduction

The aim of this list is to introduce a degree of uniformity in the way in which NMR results are reported in chemical journals, so as to ensure that experiments can be precisely repeated. It is to be regarded as a minimal list, though not all parameters are relevant to a given experiment. It should be noted that sample conditions (e.g. solvent, concentration etc.) are not part of the list, though clearly it is also essential for these to be specified.

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2. General

  1. The nucleus or nuclei studied.
  2. The instrument manufacturer and model.
  3. The resonance frequency or frequencies (preferably of the reference sample or samples).
  4. The magnetic field [optional if frequencies are given].
  5. The type(s) of pulse sequence.
  6. The referencing procedure for obtaining chemical shifts (and/or relative shielding constants).
  7. The size/nature of the sample tube/container.
  8. The temperature of the sample at the time of the measurement.

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3. Pulse conditions

  1. The RF pulse magnetic field (or equivalent in frequency units) and/or equivalent 90o pulse duration. [Note the unambiguous word "duration" rather than "width" or "length".]
  2. The flip (nutation) angle(s) and relative phases of all pulses.
  3. The spectral width (or dwell time if unambiguously defined).
  4. The acquisition time (or number of acquired data points if the dwell time is given).
  5. The number of transients (acquisitions).
  6. The recycle delay. [Note, this implies the time interval between the completion of one cycle of a pulse sequence and the start of the next one, sometimes called a relaxation delay. This is distinct from a cycle time, which is the time between analogous points of successive pulse sequence cycles].
  7. Any other relevant time intervals.
  8. The decoupling or double/multiple resonance method and conditions, including the RF magnetic field (or equivalent in frequency units and/or equivalent 90o pulse duration).
  9. Pulse shapes and relevant frequencies (for experiments with selective pulses).
  10. The magnitudes, directions, shapes and durations of any magnetic field gradients.

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4. Processing parameters

  1. Zero-filling extent.
  2. Any window function (apodization, pre-acquisition delay, resolution enhancement, line broadening).
  3. Any special baseline correction or phase adjustment procedures.
  4. Any additional processing details, such as linear prediction or maximum entropy.
  5. Any special procedures for signal quantification (e.g. deconvolution).

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5. Solid-state spectra (additional requirements)

  1. Contact time. [For cross polarization operation.]
  2. Sample rotation angle.
  3. Sample rotation rate.
  4. Use of special techniques such as DOR or DAS.

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6. Relaxation measurements (additional requirements)

  1. Number of measurement points used.
  2. Analysis method (exponential etc.).
  3. Radiofrequency field magnitude (or equivalent expressed in frequency units). [For T1r measurements.]

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7. Multidimensional spectra

  1. The time increments and the number of data points and/or the spectral width and maximum duration of evolution periods must be given for each dimension, as well as the data size after processing.
  2. For figures of multidimensional spectra, each axis should be unambiguously labelled by the variable involved (e.g. dH, dC, JCH) where possible, as well as by a frequency label such as F1, F2 etc.

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8. Additional notes

  1. Figures of spectra should have an indication of the direction of increasing frequency and the captions should state the nucleus involved. Wherever feasible, assignments of chemical shifts should be indicated on illustrated spectra.
  2. Phase cycling of all RF pulses and of the receiver should be specified when crucial to the experiment.
  3. For novel or unusual pulse sequences a timing diagram is highly recommended. If acronyms are used instead of diagrams for established sequences, a literature reference is recommended.

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