Preparation of the samples

• Amount of substance:
  For ¹H measurements: 5 - 20 mg (natural frequency: 99.9%)
  A higher amount of substance leads to broader signals and poorer resolution
  For ¹³C measurements: 5 mg per ¹³C atom (natural frequency: 1.1%)
  Smaller amounts of substance lead to longer measurement times. (half the amount of substance = four times the measuring time, etc.)

• Stinking samples should be wrapped in parafilm or filled into ground glass tubes.
  
• Deuterated solvents (anhydrous) or D₂O capillaries should be used. (D₂O capillaries not for the Fourier 300) The deuterium signal is used in the NMR spectrometer to counteract the drift of the magnetic field and to ensure the homogeneity of the magnetic field. (so-called lock) Measurements without a lock lead to poorer results.
  
• The solution should be free of suspended matter and magnetic and paramagnetic impurities.

• Filling level: 4 - 6 cm; the spectrometers are tuned to this filling level. (Shimming = tuning the magnetic field)

• The information sheet "Length of NMR tubes" must be observed.

• Only undamaged and clean tubes will be accepted.

Sample accompanying sheet

• Mandatory fields: Name, date, sample name, solvent, assistant (if available), working group, experiments → tick or possibly enter further exp. in the comments field (reverse side can also be used)

Naming:

• Samples from the OC beginner internship begin with OCA name abbreviation-...
• Samples from from the synthesis practical course begin with ISP-OC-name abbreviation-... or ISP-AC-name abbreviation-...
• Samples from research practicals start with OCF-name abbreviation-... or ACF- name abbreviation-...
• Samples from the NMR practical course begin with NMR-PR- name abbreviation-...
• Bachelor (recommendation): BA-Name abbreviation-...
• Master (recommendation): MA-Name abbreviation-...
• Other: Name abbreviation-...
• If a different measuring range is required, this is entered accordingly under "sw" and "o1p".
• sw = Width of the spectrum in ppm
• o1p = centre of the spectrum in ppm

• The coupling constants must be entered for HMQC and HMBC heterocore measurements.

Notes on cleanliness

• The NMR tubes must be tightly closed and clean (cleaned on the outside with isopropanol).

• This also applies to the vessels in which they are stored. The cotton wool in them and the sample labels must also be clean. Of course, the sample containers must also be free of damage.

• Unclean or damaged glass containers will be retained by us!

• Failure to observe this will lead to gradual contamination of the sample heads and the spinner. The consequences are: poor shim, sticky tubes in the sample head, sending the sample head to the manufacturer for cleaning → duration at least 3 months.