■= 93 = 



Certain regularities in the sorbability of the pigments appear in 

 Table IV, III, Zeaxanthin, a dihydroxy-(^ -carotene, and lutein, a dihy- 

 droxy-0(.-carotene, are more sorbed than cryptoxanthin, a monohydroxy- p - 

 carotene o Crypt oxanthin, is, in turn, more sorbed than the OL-carotene 

 and ^-carotene. Among these five pigments, the sorbability on sugar and 

 on Celite is proportional to the number of the hydroxyl groups. The 

 sorbability on magnesia is proportional to the nxamber of the hydroxyl 

 groups, to the number of double bonds, and to the number of conjugated 

 double bonds. 



Irregularities in the adsorption sequence of the pigments reported 

 in Table IV, III are due largely to variation of the sorbability of 

 rhodoxanthin and lycopene relative to the sorbability of the other pig- 

 ments. The variation of the sorbability of lycopene is due primarily 

 to variation of the sorbent, because lycopene is strongly sorbed on 

 magnesia but weakly sorbed on sugar and Celite irrespective of the sol- 

 vent. 



The variation of the relative sorbability of rhodoxanthin (Table 

 IV,III) is due primarily to variation of the solvent. In columns of 

 the three different sorbents and virith petroleum ether as solvent, the 

 rhodoxanthin is the most adsorbed pigment. In columns of Celite, addi- 

 tion of acetone causes the rhodoxanthin to be sorbed below lutein and 

 above cryptoxanthin. And in columns of sugar, addition of n=propanol 

 or of acetone causes the rhodoxanthin to be sorbed below cryptoxanthin 

 but above the carotenes. 



The effects of these polar solvents upon the relative sorbability 

 of the pigments may be attributed to two principal reactions; the com= 

 bination of the sorbent with the polar solvent and the solvation of the 



