256 CAROTINOIDS AND RELATED PIGMENTS 



tensity was secured for the unknown color solutions. No attempt 

 was made to calculate the results in terms of carotin and xantho- 

 phyll content of the leaves studied. 



Miss Goerrig mentions one or two points of interest in connection 

 with the remaining steps of the method, which were followed closely. 

 In the removal of the chlorophyll by saponification the alkali-chloro- 

 plwllines did not retain the xanthophylls as mentioned by Willstatter. 

 Again, in the final removal of the xanthophyll to ether before making 

 up the solutions for the colorimctric reading, Miss Goerrig encoun- 

 tered the most difficult part of the whole method. Contrary to the 

 statement of Willstatter and Stoll, she found it impossible to transfer 

 all the xanthophylls to ether by the slow addition of water. 



Estimation of Fucoxanthin 



The fucoxanthin content of brown algae can be determined by a col- 

 orimetric method devised by Willstatter and Page (1914). The de- 

 tails of the isolation of the pigment and its quantitative estimation 

 are given by these investigators as follows. 



The algse are pressed dry between filter papers and ground to a 

 fine meal. Except for Laminaria, for which a different treatment is 

 recommended, 40 grams of the meal are mixed with 200 grams of 

 sand and macerated with 50 cc. of 40 per cent acetone, then twice 

 with 50 cc. of 30 per cent acetone. These extracts are discarded. 

 The pigments are then extracted with pure acetone. Laminaria are 

 first cut up into small pieces and extracted with 30 per cent acetone in 

 a beaker. The pulp is then ground in a meat chopper and a weighed 

 quantity mixed with sand and extracted with 95 per cent acetone 

 and finally with anhydrous acetone until all the pigments are ex- 

 tracted. 



In all cases the pigments are transferred to ether by adding 300 cc. 

 of ether to the acetone solution and then adding distilled water. The 

 ether is freed from acetone by very careful washing with distilled 

 water and, after mixing with an equal volume of petroleum ether, is 

 ready for the extraction of the fucoxanthin. This is accomplished 

 by shaking four times with an equal volume of 70 per cent methyl 

 alcohol which has been saturated with petroleum ether, the volume 

 of the upper layer being kept constant by additions of ether after 

 each extraction. The combined alcohol extracts are freed from some 

 xanthophyll which is extracted along with the fucoxanthin by shaking 



