PROPERTIES OF THE CAROTENOIDS 



613 



are included in Figure 4 for ordinary (all-/rans)-/3-carotene in hexane, 

 while the curves for some of the commoner carotenoids are in Figures 

 5 to 13 on pages 614-618. 



The values reported for the molecular extinction of various carotenoids 

 in several solvents are found in Table 17 and in Table 18 on page 619. 



Table 17 

 Extinction Coefficients of the Carotenes at Points of Maximum and Minimum 



Absorption" 



" Adapted from J. R. Loofbourow, Vitamins and Hormones, 1, 109-155 (1943). 

 * Eth. = ethanol. 



{3) Solubility 



The carotenoids are characterized as lipids because' of their ready solu- 

 bility in the fat solvents. However, marked differences in solubility exist 

 between the carotenoids belonging to the group which are strictly hydro- 

 carbons and the group of carotenols. These differences are sufficiently 

 pronounced to offer a satisfactory criterion for the quantitative differentia- 

 tion of one group from the other when they are present in the form of a 

 mixture. 



a. Separation of the Carotenes from the Xanthophylls. When the 



