total content of the yellow anthracyclines and of their aglycones can be spectrophotometrically determined at 430 nm on a sample of the organic phase concentrated under reduced pressure quantitative determination of the single antibiotics can be obtained by preparative tlc using the above reported system the different yellow colored zones are scraped off and eluted with methanol each constituent is spectrophotometrically determined at 430 nm the antibiotic y is usually the major constituent in the fermentation broths after the fermentation is completed the active compounds are contained in the mycelia and in the fermentation liquors these anthracycline antibiotics can be extracted at ph 8 5 to 9 0 as free bases from the culture broth 34 in toto 34 with a water immiscible organic solvent such as butanol methyl isobutyl ketone chloroform methylene dichloride and ethyl acetate preferably the mycelia and the fermentation liquors are separated by filtration at ph 4 with the aid of diatomaceous earth and then extracted separately the filter cake is extracted with a water soluble solvent such as acetone or a lower alcohol preferably with methanol the concentrate is combined with the filtered broth adjusted to ph 8 5 to 9 then extracted with a water immiscible organic solvent preferably chloroform or n butanol the extracts are concentrated under reduced pressure and the anthracycline antibiotics may be precipitated by addition of a five fold volume of n hexane the constituents of the crude mixture may be fractionated and purified by column chromatographic methods further purification of the antibiotic activity and its separation into four components namely antibiotics w x y and z may be effected by silica gel column chromatography the crude orange brown.