Serum iron determinations: corrections for the bathophenanthroline and dipyridine procedures.

HE SERUM IRON DETERMINATION of Kingsley and Getchell (1) using the sensitive iron-complexing reagent, 4,7-diphenyl-1,10 phenanthroline (bathophenanthroline) appears to be useful in the clinical laboratory. However, the authors state that the procedure yields values significantly higher than the 2,2-dipyridyl reagent, but a satisfactory explanation for this difference is not readily apparent. In applying the Kingsley and Getchell procedure and Ramsay procedure (2) in our laboratories, we find that hydrolysis of serum in acid solution liberates sufficient pigments to yield serum iron values significantly too high. Gubler et al. (3) has pointed out that serum pigments interfere in photometric determinations for serum copper and must be corrected with a serum control. The need for appropriate controls for other photometric determinations has recently been emphasized by Henry and Berkman (4). In a recently reported modification of the Kingsley and Getchell procedure suitable for both copper and iron analyses (5), appropriate serum controls are used to compensate for interfering serum pigments. Our data confirm the need for a serum control with the Kingsley and Getchell procedure and Ramsay procedure for serum iron determinations. With appropriate controls, the two procedures are in agreement.