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Extraction of the Pigments 



For prevention of the hydro lytic and oxidative reactions of the 

 pigments that may take place rapidly when plant material is crushed * , 

 coarse plant material, such as leaves, was chopped finely with a very 

 sharp knife in a wooden bowl. The pigments were then extracted from 

 this chopped material with an organic solvent,, 



Although scalding or blanching of the plant material may be uti- 

 lized to destroy the oxidative enzymes and to facilitate subsequent pig- 

 ment extraction, this preliminary heat treatment is undesirable because 

 it accelerates the isomerization of the chlorophylls and of many carote- 

 noidSo Some of the isomerization reactions occur to a detectable extent 



even when the solutions have stood at room temperature for more than an 



-t. 6 

 hour or two-^' . It is desirable, therefore, to perform the extractions 



and the separations as rapidly as possible. Exposure of the solutions 



to bright light, such as sunlight, should also be avoided, 



A solvent mixture composed of 2 volumes of absolute methanol and 1 



vol\;ime of petrole\jm ether, (boiling point about 50°) j ^^s been found to 



yield very rapid extraction of the chloroplast pigments with a minimum 



of decompositionc About 5 grams of the chopped plant material, or about 



1 to 5 grams of centrifuged algal cells were mixed with about I50 mlo 



of the solvent mixture. The resultant rapid extraction isolated the 



pigments from the plant material and reduced enzymatic changes. The 



water in the fresh plant material diluted the methanol causing it to 



separate from the petroleum ether and thereby retarded allomerization 



of the chlorophyll. The petroleum e ther dissolved the pigments and 



isolated them from the plant material and from the methanol. With all 



but the most impervious plant material, the extraction was complete in 



5 to 15 minutes. 



