260 



CAROTINOIDS AND RELATED PIGMENTS 



Example 2. The extract of 10 cc. of blood serum in 10 cc. volume 

 in ether was compared colorimetrically with standard dichromate. A 

 50 mm. layer of serum extract was found to equal 15 mm. of 0.2 per 

 cent K 2 Cr 2 7 . The pigment eventually proved to be entirely xautho- 



100 



10 20 SO -fO SO 6O 70 dO O 100 IlO Z&m-m. 



CAROTIN OR XANTHOPHYLL 



Quantitative relations between 0.2 per cent K 2 Cr 2 O 7 solutions and 5 x 10- molar 



solutions of carotin and xanthophyll. 



phyll. Referring to the xanthophyll curve in Chart 1 it is seen that 

 15 mm. of dichromate equals 30.5 mm. of 0.00284 per cent xanthophyll 

 solution. 



Therefore, 0.00284 : x = 50 : 30.5 



x = 0.00173 per cent xanthophyll in the serum 

 (ignoring the sp. g. of the serum). 



