The separation of ferritin and haemosiderin for studies in the metabolism of iron

1. Ferritin and haemosiderin in diluted tissue cannot be quantitatively separated by centrifugation unless the pH is brought below 6. 2. These iron-storage substances can be separated from one another and from haemoglobin by ion-exchange chromatography on CM-cellulose, when good recoveries of total tissue iron are obtained. 3. The ferritin fraction has been identified by its solubility, its appearance under the electron microscope, crystallization with Cd²⁺ and the fact that it corresponds quantitatively to the heat-stable portion of the tissue non-haem iron.