Carotenoids chromatography-nuclear magnetic

Although saponification was found to be unnecessary for the separation and quantification of carotenoids from leafy vegetables by high performance liquid chromatography (HPLC) or open column chromatography (OCC), saponification is usually employed to clean the extract when subsequent purification steps are required such as for nuclear magnetic resonance (NMR) spectroscopy and production of standards from natural sources. 

Because carotenoids are light- and oxygen-sensitive, a closed-loop hyphenated technique such as the on-line coupling of high performance liquid chromatography (HPLC) together with nuclear magnetic resonance (NMR) spectroscopy can be used for the artifact-free structural determination of the different isomers. 

Carotenoids have also been characterized by nuclear magnetic resonance (NMR), infrared (IR), and Raman spectroscopy as well as by x-ray analysis and mass spectrometry (6). Because of their low volatility and relatively high molecular weight, the C-40 carotenoids have not as yet been separated by gas chromatography. Currently, carotenoids are primarily isolated by liquid chromatography on solid supports. 

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