X-Ray Spectroscopy in the Clinical Laboratory IV. Phosphorus; Total Blood Iron as a Measure of Hemoglobin Content

X-ray spectroscopywas applied to the determination of the total phosphorus content of serum and the iron content of whole blood (hemoglobin). Samples were placedon confined spotson paper, dried, then passedthrough the X-ray field. Concentration was then determined from the peaks as drawn on a recorder. A device is described that permits automatic assay of successivesamples dried on paper without delaysbetween readings. Samplesare placed in the field and rapidly withdrawn at 30-sec. intervals, the responseof the recorder serving as a measure of concentration. Results for total phosphorusin serum and total iron in whole blood were comparedwith those obtained by a wet ashing procedure. No signifi-cant difference with respect to both mean values and precision was observedex-cept that total iron by the wet ashing procedure was more precise. However, the X-ray technic was adequate for clinical purposes. Hemoglobin levels calculated from whole-blood iron values demonstrated that bilirubin, red cell debris, leuko-cytes, and lipids interfered in the colorimetric but not in the X-ray procedure. A hemoglobinometerbased on the X-ray spectroscopictechnic may, therefore, yield results of greater clinical significance. CONTINUING OUR STUDIES on the application of X-ray spectroscopy to clinical problems, we investigated the problem of phosphorus and iron assay. These elements, like calcium, potassium, chlorine, and sulfur, exist in blood in such concentrations that they may be ana-lyzed directly without processing of the sample (1). The technic requires placing the sample in a confined spot on paper and exposing the dried sample to the X-ray field (2, 3)