trolyte. Any Np(IV) formed may then be reversibly reduced to Np(III) at the electrode. When a large amount of Np(IV) relative to the amount of uranium is present, a separate peak for the reduction of Np(IV) may be observed at about -0.3 V vs. the SCE. The effect of an amount of neptunium (added as Np(V) sulfate) sufficient to cause slight interference with the uranium peak height is shown in Figure 2. Note the broadening of the uranium peak toward a more negative potential.The possible interference of fourteen other cations was investigated and the results are summarized in Table III. Zinc(II), Mo(V), Ti(IV), and Pt(IV) were found to interfere at the levels tested. The effect of chromium is not clear. By itself Cr (III) did not affect the uranium peak height; however, addition of Cr (III) in the presence of molybdenum caused a significant increase in peak height. No interference from Th(IV) was observed. This is important because 238Pu metal is often cast into thorium oxide crucibles, and thorium is a common impurity. It is important to note that the oxidation states given for ions listed in Tables II and III are the nominal oxidation state in which the ions were added to the electrolyte, which is a combination of a mild complexing agent and a reducing agent, i.e., sulfate and ascorbic acid.Americium was not tested separately; however, all samples contained some americium. For most samples, the weight percent of americium was about one-tenth that of the uranium. No evidence of americium interference was noted as evidenced by the agreement between DPP results and the results of other methods of uranium analysis. Americium(III) is not considered to be electroreducible in aqueous solutions, and it is likely that any reasonable amount of americium could be tolerated.Several anions were checked for interference. A fivefold concentration excess of CIO4or NO3over uranium had no effect. Phosphate and F_ interfere strongly even in small amounts and must be excluded. Chloride interferes by increasing the level of residual current in the region of the uranium peak.

No abstract

No abstract

No abstract

Provides a relatively inexpensive alternative to the use of atomic absorption spectrophotometry.