METHODS OF ISOLATION OF CAKOTIXOIDS 217 



according to Montcvcrdc and Lubimenko. The dried material is first 

 extracted with absolute alcohol, which takes out all the pigments. 

 The extract is next treated with saturated Jia(01I) 2 solution, which 

 precipitates all the pigments. The precipitate is extracted with al- 

 cohol, which extracts the rhodoxanthin, together with the carotin and 

 xanthophylls, if present. The carotin is removed by shaking with 

 petroleum ether. This removes a little of the rhodoxanthin, but the 

 bulk of the pigment remains in the alcohol. The rhodoxanthin shows 

 great crystallizability, and can be obtained in crystalline form merely 

 by evaporating the alcohol solution, whereas the xanthophyll is left 

 as an amorphous deposit. The rhodoxanthin crystals can be washed 

 free from most impurities by petroleum ether, in which the pigment, 

 like xanthophyll, is practially insoluble. 



Summary 



The principles involved in the isolation of the several carotinoids 

 from plant and animal tissues are described in this chapter. The 

 methods are also given in detail for the isolation of crystalline carotin 

 in quantity from carrots and green leaves, and of its isolation from 

 animal fat and blood in sufficient quantity for macroscopic study. 



The evidence is presented for the existence of a carotin-albumin 

 complex in blood serum, and the method described by which this 

 can be isolated. It is pointed out that this pigment-protein material 

 may play an important part in the process of fat synthesis in the 

 mammary gland of the cow and that its further study may therefore 

 throw light on the formation of milk fat. 



Methods are described in detail whereby crystalline xanthophyll 

 can be secured in quantity from green leaves and egg yolk, as well 

 as methods for separating the pigment in small quantity from eggs 

 and blood for macroscopic study. 



It is pointed out that xanthophyll, in contrast with carotin, is, in 

 most cases, readily extracted from blood serum by vigorous direct 

 shaking with ether. This is not a safe basis, however, for judging 

 the character of the carotinoid present in blood. 



The isolation of crystalline lycopin in quantity from tomatoes is 

 described, as well as the isolation of fucoxanthin from brown sea- 

 weeds. The method is given for securing crystals of rhodoxanthin. 



