QUA\TITATI\ ! I-XTIMATION OF CAROTINOIDS 251 



son than stron.urr hands, and that this was secured at a depth of 3 cm. 

 for the carotin and xanthophyll standards. 



Using the above method Monteverde and Lubimenko determined 

 the carotin (and xanthophyll) content of a number of plants. The 

 data are given in Table 18. The results are striking in so far as tin- 

 low content of carotin is concerned in comparison with the results se- 

 cured by Arnaud. The writer is not convinced that absolute alcohol 

 will give a quantitative extraction of carotin from the baryta-chloro- 

 phyll complex obtained by this method. The data in Table 18 are 

 of interest also in showing quite wide variations between the relative 

 amounts of carotin and xanthophyll in the different plants. 



TABLE 18. CAROTINOID CONTENT OF DRY GREEN LEAVES (LUBIMENKO'S METHOD) 



Carotin Xanthophyll 



Name of plant content content 



mg. per mg. per 



lOOgms. lOOgms. 



Tli n.ja oricntalis (arbor vita-) 20.8 131.7 



Viburnum Tinus 47.9 154.3 



Luff a gigantia, 61 .5 354.6 



Albizzia Julibrissin 66.7 280.9 



Ruta graveolens 94.4 387.6 



Ailanthus glandulosa 72.7 263.3 



Clematis vitalba 100.6 406.5 



Hyssopus officinalis 108.1 355.6 



Rubus caesius 106.0 396.8 



Arundinaria japonica 106.1 350.0 



Willstatter and Stoll (1913) have described in great detail a colori- 

 metric method for the quantitative estimation of carotin and xantho- 

 phylls which appears to give very accurate results. The method as 

 given is intended to be used for green plant tissues. For convenience 

 in understanding the details the method may be divided into several 

 parts, as follows: (1) Preparation of the material, (2) extraction of 

 the pigments, (3) removal of the chlorophyll, (4) separation of the 

 carotinoids, (5) colorimetric comparison of the carotinoids with stand- 

 ard solutions. 



Preparation of the material. Forty grams of fresh leaves are 

 placed in a mortar (diam. 25 cm.) with 50 cc. of 40 per cent acetone 

 and macerated quickly with 0.5 gram of quartz sand. One hundred 

 cc. of 30 per cent acetone are then poured over the apparently dry 

 mass and the whole mixed for a few minutes. The extract and leafy 

 material are then transferred to a suction filter containing a thin layer 

 of talc, and the extract sucked away. After sucking dry, the material 

 on the filter is washed with 100-200 cc. of 30 per cent acetone in small 



