A new method for serum iron and total iron-binding capacity by atomic absorption spectrophotometry. Clin. Chem

A new, atomic absorption spectrophotometric method for serum iron and iron-binding capacity is described, which utilizes 20 % (w/v) TCA plus heating at 90#{176}for 15 mm. This procedure liberates the ferric iron; precipitates the protein, facilitating removal by centrifugation; and avoids significant interferences by contaminating hemoglobin iron. The method is highly specific, accurate, and has the additional feature of requiring less time than most colorimetric or atomic absorption methods employing chelation and extraction. IN’lOST of the spectrophotometric methods for serum or plasma iron determinations suffer from at least one of three undesirable features: (1) low sensitivity of the color reaction employed, (2) turbidity in the final color solution, and (3) nonspecific background absorbance in the color solution (1). Atomic absorption spectrophotometry not only over-comes these problems, but it additionally has greater specificity and accuracy. Thus, various workers have used atomic absorption technics for the determination of iron in serum or plasma, and a variety of methods (2-4) have been developed to that end. Usually, the iron content was determined on undiluted plasma or a 1:1 dilution of plasma and deionized water. However, the high protein content of the atomized samples frequently gave erratic results. In addition, it was impossible to distinguish between serum ferric iron and hemoglobin ferrous iron in the sample. In the method of Zettner et al (4), ferric iron is freed by 1.0 N hydrochloric acid and thioglycolate, chelated with bathophenanthroline, and the chelated metal extracted into methyl isohutyl ketone. This technic not only avoids extraction of hemoglobin iron, as long as it is not present in excessive amounts, hut the organic solvent used i