Purification of dihydroporphyrins for specific activity determination by thin-layer chromatography☆

Abstract Chromatography on thin layers of confectioner's (icing) sugar can be used to purify 14 C-labeled chlorophylls a and b for specific activity determinations. With chlorophylls from plants containing lutein, a pre-development of the plate with 20% diethyl ether in light petroleum ensures adequate separation of the lutein from the chlorophyll a on subsequent development with 05 % 2-propanol in light petroleum. The specific activities of 14 C-labeled chlorophylls a and b purified by the outlined procedure agree, within the analytical error, with those obtained for identical samples purified by chromatography on columns of confectioner's sugar. The radiochemical criterion that the specific activity of the 14 C-labeled chlorophyll a or b must agree with that of the corresponding pheophytin is met.