Nuclear Magnetic Resonance

Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical technique with various applications, from the structural elucidation of complex molecules to 3D imaging of fresh tissue to simple ingredient assays. As rapid and high-throughput NMR applications have been developed for food analysis, these methods have become standard for quality assurance laboratories across the food industry. Examples of these applications include moisture or fat testing and through package analysis. NMR differs from most other forms of spectroscopy because the nucleus is the subject of analysis, and the excitation step uses radio-frequency electromagnetic energy. Whereas other spectroscopy techniques may be used to determine the nature of the functional groups present in a sample, only NMR spectroscopy can provide the data necessary to determine the complete structure of a molecule. The NMR instrument consists of a cryo-magnet with the transmitter and receiver antennae in the central bore, an electronics console with the transmitter and receiver hardware, and a data/workstation that controls all the functions of the instrument. In addition to NMR spectrometers, with both solids and liquids applications, other related instruments, such as magnetic resonance imaging (MRI), are based on the same principles but yield different information. This chapter covers the basic principles and applications of NMR spectroscopy and a brief description of relaxometry, MRI, and the use of NMR as part of a rapid moisture and fat analysis system.