Nuclear magnetic resonance (NMR) spectroscopy is common in modern research and development applications. It has found particular use in pharmaceutical research. The NMR requires liquid helium.
The NMR instrument uses a strong magnetic field to cause excitation of the sample nuclei. This results in nuclear magnetic resonance, which can be detected with radio receivers. The technique provides details of the structure of a molecule and its individual functional groups.
NMR spectroscopy is the definitive method to identify monomolecular organic compounds. Biochemists also use NMR to identify proteins and other complex molecules. NMR has largely replaced traditional wet chemistry tests such as colour reagents or typical chromatography for organic molecule identification. Drug discovery and pharmaceutical R&D are two of the most common laboratory and industrial applications for NMR spectroscopy.
Modern NMR spectrometers have a strong superconducting magnet to intensify the resolution. The magnet is super-cooled with liquid helium to reduce the electrical resistance and intensify the magnetic field. Smaller instruments using permanent magnets are also available, but give lower resolution, which might be acceptable for certain applications. Low-resolution NMR produces broader peaks which can easily overlap one another causing issues in resolving complex structures. The use of higher strength magnetic fields results in clear resolution of the peaks and is the now standard in R&D and industrial applications.
The operating principle of NMR spectroscopy is similar to the MRI scanning machines that are used for clinical diagnosis in hospitals. Both are used to create a virtual image of the subject under investigation.