X-Ray Absorption Edge Determination or Uranium in Complex Mixtures

Abstract

Uranium in the concentration range between 0.5 and 40 mg per ml is determined by an x-ray absorption edge procedure. In this procedure a molybdenum- niobium target is bombarded by the radiation from a tungstentarget x-ray tube and the intensities of the fluorescent x rays of molybdenum and niobium are measured after they have passed through an absorption cell filled with the sample solution. The measured intensities are compared to the intensities transmitted through the same cell filled with water. The L/sub I//sub I//sub I/ absorption edge for uranium occurs at a wave length between the wave lengths of the fluorescent x rays from the target, and the transmittcd intensities are related to uranium concentration by standard absorption principles. For determining between 0.5 and 40 mg of uranium per ml the relative standard deviation of the method varies from 6 to 0.34%. Defining sensitivity as that concentration of uranium equivalent to three times the standard deviation of determining a blank, 0.06 mg of uranium per ml can be measured when a cell of 3-cm path length is used. Only yttrium interferes seriously with the procedure. Approximately 5 minutes are required to convert the instrument from normal x-ray fluorescence operation tomore » absorption edge analysis. Twenty to forty analyses can be performed daily. (auth)« less