Electrochemically-Modulated Separation and Concentration of Actinides Including Uranium and Plutonium

A method has been developed and used on-line with inductively couple plasma mass spectrometry for the rapid separation and concentration of uranium prior to elemental and isotopic analysis. This methodology is termed electrochemically-modulated separation (EMS) and relies on the ability to change the analyte retention of a surface by changing (i.e., modulating) the voltage applied to an electrode exposed to the sample. In this work, EMS is coupled to an inductively coupled plasma time of flight mass spectrometer (ICP-TOF-MS); the hybrid approach is found to improve the sensitivity by nearly two orders of magnitude and vastly reduces bench top chemistry. Separation of uranium, as well as other elements, can be effected in minutes with minimal chemistry. The utility of ICP-TOF-MS for isotopic analysis of transient signals is demonstrated. Useful isotope ratios are determined directly from the analysis of a nondiluted seawater sample, arguably one of the most challenging matrices. Proof-of-principle experiments are shown that a similar approach is suitable for plutonium separations