The Determination of Iron in Biological Materials

Incident to a study of hemoglobin regeneration in the chronic, hemorrhagic anemia of dogs in this laboratory, the analysis for iron in biological materials became necessary. The difficulty experienced in such iron estimations has been reported by many authors. The variable and contradictory observations in the older literature and the multiplicity of complicated methods advocated for iron analysis emphasize these difficulties. The experience in this laboratory has been no exception to this discouraging record. At this stage of the study in 1934 Dr. C. A. Elvehjem of the University of Wisconsin kindly agreed to demonstrate the analytical method employed in his laboratory. The method of Elvehjem, which is similar in principle to those of Stugart (11) and Winter (12), has not been previously described in detail. After a thorough trial it has been found very satisfactory. It is worth while, therefore, to describe this analytical procedure, to point out details in the method whose careful observance has been found important, and to record the pitfalls experienced in some other methods. It is often stated that dry ignition of biological materials for iron analyses yields erroneous results. The wet ash method with sulfuric and nitric acids introduces a variable amount of iron arising from the traces of iron remaining in the purest samples of these acids. The factors effecting loss of iron during dry ignition have been studied and the method in use in Elvehjem’s’ laboratory of eliminating this error has proved satisfactory. Stugart (11) and Starkenstein (10) have reviewed the history