-9k' 



pigment molecules with the polar solvent. As the sorbent becomes satu- 

 rated with the polar solvent, its affinity for each pigment may vary from 

 that in the absence of the polar molecules,, This variation is a function 

 both of the nature and the concentration of the polar substances added 

 to the solvent. 



As shown by their spectral absorption properties, the carotenoid 

 pigments react with polar organic solvents. In solution in nonpolar hy- 

 drocarbons, the carotenoid pigments exhibit well-defined spectral adsorp- 

 tion bands with definite absorption maxima, but in solution in polar 

 organic solvents such as alcohols, the pigments exhibit poorly defined, 

 spectral absorption bands. This effect indicates solvation of the 

 chromophoric systems. It is most conspicuous with carotenoid molecules 

 containing keto groups as has been shown already for rhodoxanthin. Fig- 

 ure II, 2j siphonaxanthin. Figure ll,5j ^^'^ fucoxanthin, Figure 11,6, 

 These solvated molecules should exhibit relative adsorption affinities 

 quite different from those of nonsolvated or less solvated pigments. 



The variation of the chromatographic sequence with variation of 

 sorbent and solvent is greatest ndien there are large differences among 

 the pigments themselves. For example, it is much easier to vary the 

 sequence of chlorophylls, xanthophylls, and carotenes than to vary the 

 sequence of carotenes or of xanthophylls-^s^, 



\ Variation of the relative sorbability of the pigments shown in 

 Table IV, II I is related to the structure of the molecules. In columns 

 of magnesia, for example, lycopene is strongly sorbed along with the 

 zeaxanthin. But in columns of sugar and of Celite, the lycopene is 

 scarcely sorbed and forms a zone with the nonsorbed (5=carotene and 

 (X-oarotene, As the conjugated, system of lycopene is similar to that 



