NMR Facility Operation

All NMR users need to finish the Basic NMR training classes before they are authorized to operate the spectrometers. The users are allowed to schedule their own times on the spectrometers on-line.

Please choose from the following for more information: Placing sample in spectrophotometer



NMR Facility Usage Fees

All NMR Spectrometers will be using the following rates from July 1, 2011.

  • Academic Use
    • Prime Time (8 AM — 5 PM): $4/hour
    • Non-Prime Time: $3/hour
  • Industrial Use
    • Prime Time (8 AM — 5 PM): $55/hour
    • Non-Prime Time: $35/hour
  • Assisted Use
    • $100/hour
  • Other Fees
    • Low Temperature Experiments: A fee of $20/run will be charged for the cost of cryogens.

NMR Facility Scheduling Policies

The following operating policies are used for all spectrometers.

  • From 8 AM — 5 PM: A maximum time of 20 minutes per session will be allowed during this time period. Users can have more than one session if they are not continuous. No advance (a day or two advance) booking is allowed during this time zone.
  • From 5 PM — 9 PM: Maximum time allowed per session is one hour. Users can have more than one session if they are not continuous. No advance booking will be allowed.
  • From 9 PM — 8 AM (the next day): This time slot is available for longer experiments such at 1D carbon and 2D experiments. Advance booking is allowed during this time zone.
  • 400 MHz NMR in Dabney 424: The 400 MHz NMR in Dabney 424 is currently being used primarily to collect carbon spectra with a reasonable concentration during the day time. This spectrometer is available for a maximum of 2 hours per session from 8 AM — 9 PM. No advance booking is allowed in this time zone.

NMR Facility Training

Basic NMR classes are offered often during semesters. All users need to finish this class to be authorized to use the spectrometers. This class normally takes 3 to 4 sessions of 90 minutes to 2 hours. An email will be sent in advance about the meeting of this class. All students are encouraged to finish these classes well before starting the research work in the lab. Users can find a step-by-step operation of the spectrometer in the Tutorials section.

NMR Sample Preparation

The quality of your spectrum is greatly affected by the sample preparation.

  • Always use a clean and dry sample tube
  • Always use the same sample volume or solution height.
  • Recommended values for 5mm tubes is 0.6ml of solution
  • Use the depth gauge to position the sample correctly in the spinner.
  • Check that the sample tube is held tightly in the spinner so that it does not spin during an experiment.

Please use good quality NMR tubes. Etched NMR tubes should not be used.

  • All spectrometers at Dabney and Partners III: For proton spectra, dissolve 5 - 10mg of sample in ~0.6mL of deuterated solvent. The NMR tube should have a minimum of 5cm of liquid from the bottom of the tube. For carbon spectra, make the sample as concentrated as possible(~50mg or more in 0.6mL of deuterated solvent). This will reduce the spectrometer time to get a quality spectrum.
  • Solvent Purity: Many solvents absorb water which can reduce the spectrum quality. Water absorption can be reduced by storing the solvents over dehydrating agents (molecular sieves) and/or in desicators.
    Deuterated chloroform contains a trace of acid. This can lead to the decomposition of acid-labile molecules.
    For low sample quantities or obstructed resonances solvents with higher deutrium incorporation than is available in the stockroom are available for purchase through a variety of vendors (ie. CIL). Typically the '100% Deuterated' solvents are expensive and are sold in small vials.
  • Floating Particles: Best results are obtained on samples that are fully dissolved in the solvent. Filter out particles using a pipette that has a small piece of clean cotton in it.

Problems

Any Problems, Please fill out the form that can be downloaded here and email to the NMR Facility Director.

Safety Issues with Superconducting Magnets

Metal Objects, Pacemakers, Credit Cards, and Watches

The magnets on all the NMR spectrometers are very strong. They can pull metal objects out of your hands or pockets. Therefore, there is a risk of injury to the user when a metal object is attracted to the magnet(a friend's wrist was broken when a magnetic stirrer was pulled to the magnet). In addition, the metal objects can lead to extensive damage to the instrument. The metal objects do not need to be large: objects as small as staples and paper clips can cause serious damage to a spectrometer.

Pacemakers may misfunction in the presence of the magnetic field. It is advised that persons with pacemakers do not go near NMR spectrometers. Please make arrangements with the NMR staff or other co-workers to acquire NMR data. Remember, the magnetic fields of the spectrometers are reasonably strong a considerable distance from the magnet.

Credit cards will be erased by the magnetic field. Watches may be damaged by the magnetic field. Do not bring credit cards and watches in the NMR labs.

Quenches

Magnet quenches occur very rarely but can have very serious consequences. A 'quench' is the spontaneous loss of the superconducting quality of the magnet. This causes the inner core of the magnet to become very hot and results in a rapid boil-off of the liquid nitrogen and liquid helium in the dewars surrounding the magnet. Typically, a quench produces a very loud constant noise and a large white plume from the top of the magnet. During the quench, oxygen is frozen out of the air and the room becomes filled with helium and nitrogen gas. Therefore, it is absolutely necessary to evacuate the room when a quench occurs. Quenches can not be predicted and, sometimes, not prevented.