What is the purpose of seperating pigment from spinach? and what does it have to do with polarity?
Spinach leaves contain chlorophyll a,chlorophyll b and beta-carotene as major pigments and smaller amounts of xanthophylls. Their extraction is needed for the evaluation of the pigments amounts in leaves and is mostly used in the school or univercity labs for the educational purpose. The beta-carotene is nonpolar, while chlorophylls contain polar C-O and C-N bonds and magnesium ion chelated to the nitrogen atoms. This structures make chlorophylls polar molecules. That is why these pigments will separate on the low and medium polar solvents like hexane and chloroform. Beta-carotene as nonpolar will be extracted with the nonpolar solvents (benzene, xylene).