The Extraction of Pure Pigments from the Leaf. 25 



Finally the ether solution is concentrated by evaporation and 

 the concentrated solution put in a dish in a vacuum desiccator. 

 On complete removal of the ether, the chlorophyll a is left as a 

 blue black mass. 



(9) Purification of Xanthophyll. To the extract containing 

 xanthophyll obtained as described in section 5, 4 to 5 litres of ether are 

 addedand a quantityof water. Any chlorophyllb that may be present 

 is removed by saponifying it to chlorophyllin by shaking with 30 to 

 50 c.c. of methyl-alcoholic potassium hydrate. The chlorophyllin 

 is removed by repeated washing with water. 



The ether solution of xanthophyll is dried with sodium sulphate, 

 evaporated to 30 c.c, and 200 to 300 c.c. methyl alcohol added. 

 Complete removal of the ether is effected by evaporating down 

 further and filtering the hot solution. On cooling, xanthophyll is 

 deposited in the form of crystals forming shining plates. Water 

 may be added to make the separation of the xanthophyll complete. 

 The yield of xanthophyll from 2 kilos of dried nettle leaves is 0-8 

 gram. 



(10) Purification of Carotin. The carotin is easily obtained. 

 The extract containing it, obtained as indicated in section 5, is 

 evaporated in vacuo at 40''C., and the oily residue treated with 

 300 c.c. of 90% alcohol. The carotin begins to separate out 

 immediately in shiny steel blue crystals. Crystallisation is complete 

 on standing in the cold. 



Any colourless impurity present in the crystalline mass is 

 dissolved in petrol ether. 200 to 300 c.c. of this are therefore added 

 and the carotin filtered from it. The purification is completed by 

 treatment with a mixture of two parts of petrol ether to one part 

 alcohol. The result is a yield of 0-25 gram of carotin from 2 kilos 

 of dried nettles. 



