CHAPTER III 

 The isolation of carotenoids 



The isolation of carotenoids from vegetable or animal sources often presents 

 difficulties, especially if extensive experience in this field is lacking. An attempt 

 will therefore be made in the present section to describe some general methods 

 of isolation. These have to be adapted in particular cases to take account of 

 the mode of occurrence of the pigments and of the materials which accompany 

 them. 



The usual course of isolation consists of the following parts: 



1. Preparation of the materials to be examined and extraction of the 

 carotenoids. 



2. Division of the carotenoids into hypophasic and epiphasic constituents. 



3. Separation of the pigments in the two phases and preparation in a 

 crystalline condition. 



The individual steps are dealt with in more detail in the following section. 

 No attempt has been made to summarise all the usual methods employed; 

 instead, a few of the well-tried and common methods are given which are 

 successful in most cases. 



T. EXTRACTION OF CAROTENOIDS 



Before the extraction of the carotenoids, the vegetable or animal material 

 must be dried (dehydrated). With blossoms or fruit or other parts of plants, 

 this is most easily accomplished by drying in the sun (preferably in a current 

 of air), or in a well-aired room at 40-50° C. It is important that the material 

 should be spread in thin layers and should be turned from time to time in order 

 to achieve as uniform a drying as possible and in order to prevent fermentation 

 which would destroy the carotenoids. If it is not possible to dry the material 

 in this way, as is sometimes the case with algae, marine plants, or animals, the 

 dehydration may be carried out by submersion in solvents such as acetone, 

 methanol, ethanol, etc. 



The extraction can be carried out by means of a wide variety of solvents. 

 The following are most commonly used: benzene, petroleum ether, ether (free 

 References p. 28. 



