THE DETERMINATION OF IRON IN SbllALL VOLUXSES OF BLOOD SERUM*

In an effort to find practical means of distinguishing iron deficiency anemias from other types in large population groups, an investigation was made of the possibility of measuring iron in an amount of blood serum obtainable from the finger. Iron deficiency anemias are characterized by low serum iron, while other states of diminished hemoglobin formaCon show normal or even high values for serum iron (l-4). The prevalence of iron deficiency anemias in large population groups has not been widely investigated, owing partly to the difficulty of obtaining necessary quantities of blood for analysis and partly to the troublesomeness of existing methods. Present methods require 1 to 10 ml. of blood serum and timeconsuming techniques. Most widely used of the methods for iron in blood serum are those involving color reactions of ferrous iron with a,&-bipyridyl (5, 6) or ophenanthroline (4, 7) and of ferric iron with thiocyanat,e ion (1,8-10). Of these three reagents, thiocyanate ion appeared to offer advantages for a simple microprocedure. Both bipyridyl and o-phenanthroline require several steps for their use (pH adjustment and reduction of ferric to ferrous iron prior to color formation) which it is possible to avoid by using a thiocyanate procedure. It has been found possible, with thiocyanate ion, to measure iron with satisfactory precision in 20 c.mm. of serum. In this method, which is described below, acid and thiocyanate ion are added as one reagent to the serum and the iron thiocyanate is extracted directly from the mixture with isoamyl alcohol. This avoids the preparation of serum filtrates and improves the extraction of iron from the serum proteins. In addition to a description of the procedure, illustrative data are presented; viz., the daily and hourly variation in serum iron in several normal persons.