Carotenoids functional groups identification

The use of chemical methods for determination of the structures of carotenoids has been extensively reviewed (Liaaen-Jensen, 1971). Although physical methods have become increasingly important in the determination of structure, a number of chemical methods are still useful. Of particular value are those which can be carried out rapidly and require only small amounts of material. These methods have been discussed by Moss and Weedon (1976), and a brief summary is found below. Chemical methods are useful in the identification of certain functional groups, and they can be used to confirm data obtained by spectroscopic methods. 

Some carotenoids are obtained in the laboratory from another related carotenoid, by means of partial synthesis, which include the reactions described in the identification of functional group section. For example, auroxanthin and luteoxanthin are obtained from violaxanthin by acidification. Neochrome and mutatoxanthin are obtained from neoxanthin and antheraxanthin, respectively, using the same procedure. The Z- 3-carotene isomers are prepared by reflux heating at 200°C an acetone solution of aU-E 3-carotene obtained from a pigment extract of carrot. ... 

In addition, the identification of carotenoid pigments includes the characterization of the functional groups, which can occasionally be inferred from the UV-visible spectmm. IR spectroscopy, although not very applicable to the identification of carotenoid pigments, is especially selective in determining the presence of particular... 

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