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How it Works
All nuclear magnetic resonance technology, including NMR spectroscopy, is based on two physical phenomena:
- Chemical Shift: all nuclei containing an odd number of protons and neutrons have ‘spin,’ an intrinsic type of movement (also called resonance). This movement is slightly different for different protons in a given molecule, and can change depending on the chemical environment.
- The Zeeman Effect: this is what happens when a spectral line (an emission or absorption point in an otherwise uniform spectrum) is split into components while in the presence of a magnetic field.
In NMR spectroscopy, magnetic nuclei are aligned with a constant magnetic field. This alignment is then disturbed by applying an alternating magnetic field to the nuclei. Both NMR spectroscopy and NMR imaging (often used in medical diagnosis) analyze the response of the nuclei to the alternating magnetic field to gather information about the composition of the sample under analysis.
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Applications of NMR Spectroscopy
NMR spectroscopy can provide an enormous amount of information—including physical, chemical, structural, and electronic—about samples under analysis. NMR spectroscopy has applications in medicine, chemistry and other fields of scientific research, industry,
Determining molecular structure and conformation of a sample and examining interactions between molecules can often only be achieved via NMR spectroscopy in conjunction with mass spectroscopy. Very often this type of research is critical to further or complete a given project (and determining structure and conformation is also important in obtaining intellectual property rights).
NMR spectroscopy is also vital for studying cell metabolism, due to the fact that metabolism is based on interactions between molecules and cells. NMR allows these types of studies to be carried out non-invasively, as it can be used to detect the presence of metabolites and chemical energy produced by cells.
Industrial processes such as reaction and process monitoring, and content and purity checks, often involve NMR spectroscopy. The specificity of NMR makes it highly suitable for monitoring and optimizing dynamic reactions and processes. Content and purity checks use NMR spectroscopy to monitor the quality and purity of batches of certain types of manufactured products, and to determine the composition of mixtures. NMR-based monitoring and testing is particularly useful because it can be done non-destructively—that is, without destroying the item being examined.
The ability of NMR spectroscopy to provide non-destructive analysis is actually highly useful in biological research because samples can be studied for extended periods using NMR, whereas biochemical experiments might destroy the samples.