High-resolution Magic-angle Spinning (HR-MAS) NMR Spectroscopy

Today, numerous analytical tools are available for metabolomics research; $^1$among them, high-resolution $^1$H liquid-state NMR spectroscopy offers a quantitative, non-destructive high-throughput method for rapid analysis of biospecimens. Therefore, $^1$H liquid-state NMR is widely used and is considered a convenient screening tool to discriminate between specimens of different biological origin. $^{2,3}$ One reason for this success is that in liquid-state NMR the samples are homogeneous (e.g., biofluids), permitting the acquisition of sharp signals (up to 0.001 ppm) for rich metabolic screening. Conversely , semisolid samples like tissue biopsies, whole cells and organisms are heterogeneous in nature and give broad NMR lines that hamper any precise and detailed metabolic investigation. This broadening is caused by the variation of the magnetic susceptibility in intercellular and intracellular boundaries. $^{4,5}$ However, in the early-mid 1990s an NMR technique emerged called high-resolution magic-angle spinning (HR-MAS) that extended the CHApTeR 5