Analysis of fission products using capillary electrophoresis with on-line radioactivity detection

Capillary electrophoresis has been used to separate metal ions characteristically associated with nuclear fission. Indirect UV absorbance and on-line radioactivity detection were used simultaneously to monitor the analytes. The radioactivity detector consists of conical plastic scintillating material with the capillary passing through the center to provide a 4π detection geometry. The wide end of the cone is optically coupled to a photomultiplier tube. Transient isotachophoretic techniques were employed to stack large volumes of samples which had low specific activities. Radioactivity detection of (152)Eu and (137)Cs was achieved at the nanocurie level for 80-100 nL injections. The detector is approximately 80% efficient, enabling samples resident in the detector window for 0.1 min to be reliably assayed. The separation of (137)Cs and (137m)Ba isotopes, which are in secular equilibrium, was modeled to demonstrate the effects of the rapid decay of (137m)Ba.