Serum copper and iron on a single sample.

HE IMPORTANCE OF THE QUANTITATIVE ANALYSIS OF SERUM IRON has been long established (1, 2, 3), while the worthiness of the determination of serum copper is becoming of increasing interest (4, 5, 6). Therefore, it would be of real value if the concentration of both metabolically interrelated constituents of serum (7, 8, 9) could be determined accurately. It has recently been shown that copper and iron, when present in known amounts, could be accurately determined by the employment of mixed phenanthrolines, either individually or on the same sample, in an aqueous or an organic phase, by the use of simultaneous mathematical equations (10). Since it is theoretically possible to determine several constituents by simultaneous spectrophotometry in the same phase, these two metals can be analyzed with accuracy (11), providing that there is no interaction between the two metals and the cornplexing agents selected as specifics for a given matrix containing the two metals. Although several possibifities exist with respect to the choice of phenanthrolines for the stated purpose, 1,10-phenanthroline (orthophenanthroline) was shown to be a specific reagent for iron, and 2,9-diinethyl-4,7-diphenyl-1,10-phenanthroline (bathocuproine), a specific reagent for copper. It will be shown that neither complexing agent interferes with the other when used in mixtures of the two metal ions. The procedure to be described involves acid destruction of the organic material present, with an initial measurement of the iron as the ferrous-1,10-phenanthroline complex, followed by the ex-