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NMR Spectrometer in Drug Discovery


Writer(s): Steve Scherer, John Harwood

Purdue’s Interdepartmental NMR Facility is getting remarkable results from its newest NMR spectrometer. The Bruker AV-III-HD 500 NMR instrument is located in B055 of the Drug Discovery Building and is available for use by any qualified NMR operator.

“The new spectrometer is equipped with a BBFO cryoprobe Prodigy, which uses Bruker's new liquid-nitrogen cooled cryoprobe technology.  This probe provides a sensitivity improvement of greater than a factor of three when compared to our existing equipment for 13C and other X-nuclei observation.  This new spectrometer is by far the most sensitive in our facility for these types of experiments and also for 19F observation.  A 13C experiment which would require overnight data acquisition on one of our other spectrometers can be completed in approximately one hour on the new spectrometer,” said John Harwood, Director of the Interdepartmental NMR Facility.

The new spectrometer makes it possible to obtain spectroscopic data that would not have been possible with our existing equipment.  For example, Dr. Harwood recently worked with graduate student Chris Clark of the Bart Lab to obtain 13C spectra on paramagnetic uranium compounds.

"Typically, 13C spectra of paramagnetic species are very difficult to obtain, and this was not possible using our previous instrumentation. However, the enhanced sensitivity of this 500 MHz NMR spectrometer has now made acquisition of this data possible, providing an additional spectroscopic handle for assignment of these challenging uranium complexes," explained Associate Professor Suzanne Bart, an inorganic chemist.

Qualified users of PINMRF TopSpin spectrometers will be able to use the new spectrometer after attending a brief overview session given by Dr. Harwood.  Users may schedule a session either through Ms. Donna Bertram or by contacting Dr. Harwood directly.

Click on images for larger view:

NMR image

The AV-II-HD-500 NMR is unique amongst PINMRF's spectrometers in that it has an actively-shielded magnet.  This results in the radial 5G-line fringe field being within the magnet's footprint, thus enhancing safety for the users and the magnet itself.

NMR user image 

The new spectrometer is controlled by TopSpin software (version 3.2) running under Linux.

Sample spectra image

Example of the carbon-13 sensitivity test spectrum using 10% ethylbenzene.  The new spectrometer achieves a signal-to-noise ratio of > 850:1.  This is 3.5X the next-best PINMRF spectrometer result of ca. 240:1.

NMR is one of several centers for molecular characterization connected to Purdue Chemistry. Other centers include: Mass Spectrometry, Imaging and spectroscopy, and X-Ray Crystallography.  Users needing more information about instrumentation resonance can contact Dr. R. Michael Everly of Purdue Chemistry's Amy Instrumentation Facility.