Nuclear Magnetic Resonance (NMR) is not easy to describe in a few paragraphs, let alone understand. Therefore, this description of NMR takes a simplistic point of view. There is much more to NMR than is contained here.
The Varian EM360A NMR was purchased in the early to mid 1980s. This instrument was state of the art in the early 80's, but the advances in NMR technology outpaced our equipment. However, we kept it functioning with the original chart recorder and some "custom-engineered" modifications for the felt-tipped pen. In 2002 we purchased an Anasazi Instruments Eft upgrade for this instrument. The Eft upgrade converted our continuous wave instrument (that swept through a series of magnetic field strengths one at a time) to a pulsed Fourier transform NMR controlled by a Windows 2000 PC. Our instrument is now capable of performing both one- and two-dimensional NMR techniques.
We also have the capability to detect not only hydrogen-1, but carbon-13, fluorine-19, silicon-29, and phosphorous-31. The adjacent spectrum is an example of a carbon-13 NMR. The reason it has both positive and negative peaks is that it is the result of an Attached Proton Test. This spectrum not only gives information about the electronic environment surrounding the carbons in our sample molecule, it also indicates how many hydrogens are attached to each carbon. The peaks pointing down correspond to carbons with 0 or 2 hydrogens attached. The peaks pointing up correspond to carbons with 1or 3 hydrogens attached.
NMR spectroscopy is one of the most powerful tools in determining the structure of organic compounds. Using the techniques described above (and a number of others) an NMR spectroscopist can ascertain the structure of a compound. All that is needed is approximately 50 milligrams of a pure sample. As a result NMR spectroscopy is used extensively in a number of applications.
Suppose you decided to come up with a new, cheaper synthesis of aspirin. How would you know if you had actually made aspirin. NMR spectroscopy could help you confirm that your product is aspirin.
Suppose you isolated a new cure for malaria from some natural source (like skunk fur, for instance). Since there are inherent disadvantages to isolating compounds from natural sources it is often advantageous to identify the active ingredient and then make it synthetically in the lab. NMR spectroscopy would be the tool to help determine the structure of the active ingredient.
NMR spectroscopy can even be used to determine the three-dimensional shape of a molecule. Techniques have been designed to identify atoms that are close to one another in space while not necessarily being attached to adjacent atoms. These techniques are important in biochemistry, where the overall shape of a molecule often dictates its behavior
Vendors of NMR Spectrometers