HR-LS-NMR / High-Resolution Liquid-Sate Nuclear Magnetic Resonance

High-Resolution Liquid-State NMR (HR-LS-NMR) spectroscopy is used for structure elucidation and characterization of molecules and materials in solution. The method is based on the interactions of nuclear spins of the atoms in the molecules with a powerful static magnetic field created by an energized superconducting coil immersed in liquid Helium. The NMR active isotopes of the nuclei (spinning positive charges) possess angular momentum and a magnetic dipole moment. Thus when placed inside the strong magnet assume discrete orientations (energy levels) with respect to the external field. When a pulse at the correct resonance frequency (energy) for a nucleus in the sample induces transitions among the energy levels, signals are detected at characteristic frequencies (chemical shifts). In liquids, the rapid tumbling of molecules averages anisotropic (direction-dependent) effects resulting in narrow spectral lines close to 1 Hz with clearly defined multiplets, revealing the fine detail of interactions among nuclei and electrons in the molecule that are translated to bond connectivity and spatial proximity of the atoms. NMR experiments using a variety of specifically designed pulse sequences can provide a wealth of information regarding the exact molecular structure of small, medium and very large molecules as well as 3D molecular structures of complicated systems.

Moreover, specific applications of interest for researchers as well as the industrial sector include: structure elucidation of specific additives or contaminants and pollutants; quantitative analysis (chemical compo­sition determination, formulation investigation, raw material fingerprinting, mixture analysis, sample purity determination); compound identification or presence confirmation in mixtures; identification and conformational analysis of chemicals, synthetic or natural ; characterization of soluble materials (e.g. polymers); monitoring of compound stability and investigation of chemical transformations with time or temperature.