Electrochemically modulated separations for rapid and sensitive isotopic analysis

The desire for more rapid and sensitive analytical determinations of actinides in the environment is being addressed in our laboratory through the development of electrochemically modulated separations (EMS) coupled to multiple ion counting inductively coupled plasma mass spectrometry (MIC-ICP-MS). This work is focused on the characterization of EMS separations of U and Pu in swipe materials. EMS provides electrochemically controlled surface complexation of either U(IV) or Pu(IV), depending on the potential applied to an anodized glassy carbon electrode. The accumulation and rinse yields ~90 % recovery efficiency, matrix elimination, and analyte concentration of the selected actinide. All this is performed solely under the control of the applied potential. Once isolated, the concentrated actinide is released into a ~1 μL volume of dilute (0.5 M) HNO3, resulting in a volumetrically concentrated transient signal that is ideal for multiple ion counting detection. Coupled with a Thermo Fisher Scientific Neptune Plus MIC-ICP-MS, atom utilization efficiencies are normally 1 %, comparable to the gold standard thermal ionization mass spectrometry (TIMS), but only requiring 20 min for separation and analysis; whereas TIMS requires >50 h for off-line separation, filament preparation, and isotopic analysis. Method and analytical figures of merit will be highlighted.