Nuclear magnetic resonance LC-NMR

Liquid Chromatography Nuclear Magnetic Resonance (LC/NMR) Systems... 

Liquid chromatography-nuclear magnetic resonance (LC-NMR) combines the separating power of LC with the structural elucidation capabilities of NMR. It is now possible to separate and elucidate the structures of components in a mixture on-line using this technique. It is most often used to identify natural products, novel compounds and metabolites. 

Efficient detection and rapid characterisation of natural products play an important role as an analytical support in the word of phytochemists. The identification of a metabolite at the earliest stage of separation is a strategic element for guiding an efficient and selective isolation procedure. In this respect, the role of hyphenated techniques such as high performance liquid chromatography coupled to mass spectrometry (LC/MS) or to nuclear magnetic resonance (LC/NMR) has became of great interest. 

In our laboratory, for the screening of crude plant extracts, HPLC coupled with UV photodiode array detection (LCAJV-DAD) and mass spectrometry (LC/MS) has been mainly used [1,3,4]. Recently several trials have also shown that HPLC coupled with nuclear magnetic resonance (LC/NMR) is a very powerful complementary technique for the on-line plant metabolite identification [5,6]. This new tool will now be also implemented to the existing LCAJV/MS configuration [7]. 

R636 K. Kawaguchi, T. Nakano and K. Kimura, How Do You Use Liquid Chromatography-Nuclear Magnetic Resonance (LC-NMR) Effectively for Structural Determinations of Pharmaceutical Impurities and Metabolites ,... 

When two compounds with very close, or even super-imposable, retention times and identical UV spectra are found in a chromatogram, it is necessary to use more sophisticated detectors that can yield much more structural information without requiring the isolation of the compounds. LC-mass spectrometry (LC-MS) and LC-nuclear magnetic resonance (LC-NMR) are often used, as it will be presented later. 

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