NMR Spectroscopy: Principles and Instrumentation

Abstract

The objective of this chapter is to familiarize the reader with nuclear magnetic resonance (NMR) spectroscopy, its basic principles, its utility as an analytical tool for investigating biofluids, and to describe the instrumentation and related hardware necessary to operate a functional NMR-based metabonomics laboratory. Nuclear magnetic resonance spectroscopy is a powerful approach because it combines the provision of detailed molecular information with thepossibility of understanding whole molecule dynamic properties such as diffusion, plus the ability to carry out quantitation. Although powerful in its own right, NMR spectroscopy can be regarded as complementary to other analytical chemical techniques. For example, it can provide information on substances with no UV chromophores such as carbohydrates. It is a universal detector in that if the molecule under study contains NMR-active nuclei these should be detectable, unlike in mass spectrometry where analyte observation can be influenced by selective ionization. Most NMR spectroscopic experiments are carried out in solution for the purpose of identifying the structures of small chemical molecules, including natural products, but there is a wealth of high resolution applications in other areas, such as determining the threedimensional (3D) structures of proteins as well as analyzing complex biological mixtures such as biofluids for metabonomics applications. In addition, there is much effort devoted to solid state NMR spectroscopy where special techniques have to be used to overcome very broad NMR peaks and hence to recover useful chemical information. Finally, NMR spectra can be obtained from living humans and animals and in vivo NMR or magnetic resonance spectroscopy (MRS), as it is known, has found use in disease diagnosis. The same technology and principles lie behind magnetic resonance imaging (MRI), now widely available in hospitals for clinical diagnosis.