A spectrochemical method for the determination of 10-1000 ppm tantalum and 20-1000 ppm tungsten in plutonium metal is described. Chemical separation by precipitation of the plutonium as insoluble plutonium trifluoride, centrifuging, and sampling the supernatant solution is well suited to the glove box operation necessary in handling plutonium. Excitation is by graphite spark; spectra are recorded photographically; and concentrations are determined by standard photometry practices using an emulsion calibration-analytical curve technique with a molybdenum internal standard.
H. N. Barton, "Optical Emission Spectrographic Determination of Tantalum and Tungsten in Plutonium," Appl. Spectrosc. 19, 159-162 (1965)