Simultaneous quantitation of seven elements by an x-ray fluorescence system for the microsphere method

An automated x-ray fluorescence system with a low Compton background was designed utilizing a metal filter, electronic devices, a polarized x-ray for element excitation, a Si(Li) detector, and a commercially-available x-ray tube. Each of the elements Rb, Mo, Ag, I, La, and Gd was tested in order to select a single optimal filter. A low Compton background and a high count rate over a wide spectral range were obtained with a filter optimized for Ag. Regions of interest were chosen for Kα peaks of Zr, Mo, Rh, Ag, Sn, I, And Ba. the net Kα peak areas were computed by subtracting the Kβ counts from the total net counts in the regions of interest. An excellent linear relation was obtained between the computed Kα net counts and their concentrations. The net count rates (cpm/ppm) were 29.34 (Zr) 46.56 (Mo), 69.78 (Rh), 81.60 (Ag), 77.75 (Sn), 70.30 (I), and 74.13 (Ba). All seven elements can be used for nonradioactive microspheres with satisfactory counting statistics for simultaneous measurements of regional blood flows