The Determination of Iron in Biological Materials

In an attempt to find a method for the determination of iron that could be used for the clinical study of iron metabolism, certain calorimetric procedures (1, 2) were studied. Some difficulties were encountered with these techniques and especially in their adaptation to the measurement of minute amounts of iron in such diverse materials as blood, food, feces, and urine. This led to the investigation of volumetric methods, with the final adoption of the titanium method, which proved eminently satisfactory. In 1903 Knecht (3) and Knecht and Hibbert (4) described an oxidation-reduction reaction for the titration of ferric iron, involving the use of a dilute solution of titanium chloride. Thornton and Chapman (5) in 1921 studied the chemistry of the reaction, confirmed its accuracy, speed, and relative simplicity, and defined more precisely its sphere of usefulness and the factors which modified it. The titanium method was first adapted to the determination of iron in biological materials by Jahn (6) in 1911. Peters (7) in 1912 used the Jahn modification, after changing the method of ashing, for his studies on the iron content of hemoglobin. Brukl (8) utilized titanium for the microestimation of iron, but his procedure was essentially the same as those previously described. Pincussen and Roman (9) in 1931 found the method satisfactory for the determination of iron in blood and organic materials, but L&szl6 (10) in the same year decided that the Jahn modification was less accurate for blood iron than Willstatter’s calorimetric estimation of hemoglobin. The procedure which has finally been adopted contains certain technical details which contribute to convenience and accuracy